He lost both of his parents in the big earthquake, but ________ for him, a kind couple adopted him

and took good care of him.[ ]

A. suddenly  

B. naturally

C. obviously  

D. luckily

鸟类的繁殖大多在春天进行，具有时间为一年的性周期。下图为某鸟类体内一个性周期的激素调节过程，请据图分析回答：

如果在养鸡场，使鸡多产蛋，据图示信息应采取的措施是（）。