The world's earliest known fish hooks   show that humans fished in the open sea for much longer than previously thought. Past studies have shown that early humans were able to cross the open ocean as far back as 50,000 years ago, but evidence that they could fish while in the open sea dated back only to 12,000 years ago.               "In most areas of the world, evidence for our early ancestors' coastal exploitation   was drowned by rising sea level," said researcher Sue O'Connor.               Now O'Connor and her colleagues have found evidence of prehistoric fishing tools and the remains of large fish such as tuna    at a cave shelter known as Jerimalai, located in the Southeast Asian island nation of East Timor. Their discovery uncovered fishing hooks made from bone that dated back to about 42,000 years ago.               "It's possible that people caught the tuna in the deep channel that lies off the coast of the Jerimalai shelter," O'Connor said.               The site, first uncovered in 2005, also included bone points, shell beads, the remains of fish, turtles, bats and birds, and nearly 10,000 stone tools. The island of Timor has very few land animals overall and only small birds call the island home, perhaps explaining why the ancient people here went fishing. About half the fish remains at the site came from fish such as tuna. Catching such fast-moving fish requires much planning and complex technology, suggesting that early humans developed these skills earlier than previously thought.               Some other scientists might say that most of the fish bones seen are from young fish, and thus might have been caught more easily off the coast as opposed to in open waters. While this may be the case, it's still not easy to catch tuna -- it requires nets set in deep water. According to Sue O'Connor, evidence for our early ancestors' coastal exploitation   _  .
indicated tuna was a common dish for our early ancestors showed the trend of sea movement was difficult to find was buried in cave shelters
Question: The world's earliest known fish hooks   show that humans fished in the open sea for much longer than previously thought. Past studies have shown that early humans were able to cross the open ocean as far back as 50,000 years ago, but evidence that they could fish while in the open sea dated back only to 12,000 years ago.               "In most areas of the world, evidence for our early ancestors' coastal exploitation   was drowned by rising sea level," said researcher Sue O'Connor.               Now O'Connor and her colleagues have found evidence of prehistoric fishing tools and the remains of large fish such as tuna    at a cave shelter known as Jerimalai, located in the Southeast Asian island nation of East Timor. Their discovery uncovered fishing hooks made from bone that dated back to about 42,000 years ago.               "It's possible that people caught the tuna in the deep channel that lies off the coast of the Jerimalai shelter," O'Connor said.               The site, first uncovered in 2005, also included bone points, shell beads, the remains of fish, turtles, bats and birds, and nearly 10,000 stone tools. The island of Timor has very few land animals overall and only small birds call the island home, perhaps explaining why the ancient people here went fishing. About half the fish remains at the site came from fish such as tuna. Catching such fast-moving fish requires much planning and complex technology, suggesting that early humans developed these skills earlier than previously thought.               Some other scientists might say that most of the fish bones seen are from young fish, and thus might have been caught more easily off the coast as opposed to in open waters. While this may be the case, it's still not easy to catch tuna -- it requires nets set in deep water. According to Sue O'Connor, evidence for our early ancestors' coastal exploitation   _  .
A. indicated tuna was a common dish for our early ancestors
B. showed the trend of sea movement
C. was difficult to find
D. was buried in cave shelters
Answer: