There once lived in China a very foolish king and queen. One day the queen had a baby daughter. When they saw their baby, they both cried out, "My goodness! How small it is! It's hairless and toothless! It's a monster!" They sent for all the doctors in the country and ordered them to prepare some medicine for her. "When she drinks your medicine, she must grow to the right size and have hair and teeth," the king said, "If you don't do this, you'll have a beating." The doctors thought it impossible, but they dared not say anything against the king's order. Just then and old doctor stepped forward. "Oh, we shall certainly obey your order," he said, "but it takes time. We have to dig a mineral from the Kun Lun Mountains when the snow melts for the second time. The snow melts on those mountains only once in six years. So we need twelve years." At last the king agreed and the doctors took away the little princess. On her twelfth birthday, they brought her back to her parents with long black hair and beautiful teeth. The king and queen were very happy and gave the doctors expensive presents. The old doctor wanted to keep the king's daughter for twelve years because   _  .
they needed a lot of different plants they need a lot of different minerals this would give the baby time to grow up they had to dig a mineral the snow melted for the second time
Question: There once lived in China a very foolish king and queen. One day the queen had a baby daughter. When they saw their baby, they both cried out, "My goodness! How small it is! It's hairless and toothless! It's a monster!" They sent for all the doctors in the country and ordered them to prepare some medicine for her. "When she drinks your medicine, she must grow to the right size and have hair and teeth," the king said, "If you don't do this, you'll have a beating." The doctors thought it impossible, but they dared not say anything against the king's order. Just then and old doctor stepped forward. "Oh, we shall certainly obey your order," he said, "but it takes time. We have to dig a mineral from the Kun Lun Mountains when the snow melts for the second time. The snow melts on those mountains only once in six years. So we need twelve years." At last the king agreed and the doctors took away the little princess. On her twelfth birthday, they brought her back to her parents with long black hair and beautiful teeth. The king and queen were very happy and gave the doctors expensive presents. The old doctor wanted to keep the king's daughter for twelve years because   _  .
A. they needed a lot of different plants
B. they need a lot of different minerals
C. this would give the baby time to grow up
D. they had to dig a mineral the snow melted for the second time
Answer: