Elephants and people are in competition for space. In much of Africa, elephants are now put in national parks. Elephants suffered a serious and steady decrease in numbers in the 1970s. This was the same time when scientists were beginning to learn a great deal about elephants and their behavior. Studies through the 1980s and into the 1990s showed a lot about their sounds and methods of communication. In Kenya alone, in the 1970s and 1980s, the elephant population decreased from 170,000 to 25,000. The sharp drop in numbers was the result of poachers   illegally killing elephants for their ivory. The price of ivory went from $3 a pound to $50 to $100 a pound. Africa became very attractive to poachers. Bull elephants carried the largest tusks  , so they were more often killed. With males gone and older females killed by poachers as well, there were many young elephants unable to benefit from the wisdom of the older females and matriarchs, who lead the herds. Kenya took a stand, international trade in ivory was officially forbidden, and $3,000,000 worth of confiscated   ivory was burned in Kenya. The following year, only 50 elephants were lost to poachers in Kenya instead of 3,000. But Kenya has the fastest growing human population in the world. People throughout Africa won't tolerate elephants eating their crops and destroying their livelihoods. In South Africa, elephants live behind the fences of national parks. In some parts of Africa, big-game hunters pay a lot of money to hunt elephants. This keeps their numbers down, and the money goes toward conservation. In Kenya, there were some attempts at birth control to keep the elephant population at manageable numbers to reduce conflicts with people. Faced with a growing human population, elephants are losing the battle for space. It's unlikely, though, that they will become extinct. They will live in natural parks that bring tourists to Africa as well as India and other parts of Asia. The money from tourism will help elephants to survive. In the 1970s and 1980s,   _  .
scientists learned little about elephants most ivory was sold at a reasonable price many young elephants are gaining less wisdom the elephant population decreased because of the terrible climate
Question: Elephants and people are in competition for space. In much of Africa, elephants are now put in national parks. Elephants suffered a serious and steady decrease in numbers in the 1970s. This was the same time when scientists were beginning to learn a great deal about elephants and their behavior. Studies through the 1980s and into the 1990s showed a lot about their sounds and methods of communication. In Kenya alone, in the 1970s and 1980s, the elephant population decreased from 170,000 to 25,000. The sharp drop in numbers was the result of poachers   illegally killing elephants for their ivory. The price of ivory went from $3 a pound to $50 to $100 a pound. Africa became very attractive to poachers. Bull elephants carried the largest tusks  , so they were more often killed. With males gone and older females killed by poachers as well, there were many young elephants unable to benefit from the wisdom of the older females and matriarchs, who lead the herds. Kenya took a stand, international trade in ivory was officially forbidden, and $3,000,000 worth of confiscated   ivory was burned in Kenya. The following year, only 50 elephants were lost to poachers in Kenya instead of 3,000. But Kenya has the fastest growing human population in the world. People throughout Africa won't tolerate elephants eating their crops and destroying their livelihoods. In South Africa, elephants live behind the fences of national parks. In some parts of Africa, big-game hunters pay a lot of money to hunt elephants. This keeps their numbers down, and the money goes toward conservation. In Kenya, there were some attempts at birth control to keep the elephant population at manageable numbers to reduce conflicts with people. Faced with a growing human population, elephants are losing the battle for space. It's unlikely, though, that they will become extinct. They will live in natural parks that bring tourists to Africa as well as India and other parts of Asia. The money from tourism will help elephants to survive. In the 1970s and 1980s,   _  .
A. scientists learned little about elephants
B. most ivory was sold at a reasonable price
C. many young elephants are gaining less wisdom
D. the elephant population decreased because of the terrible climate
Answer: