单选题

　　[阅读选择]In the next stage， from three to five years old， curiosity knows no bounds. Every type of suitable toy should be made available to the child， for trying out， experimenting and learning， for discovering his own particular ability. Bricks and jigsaws（七巧板） and construction toys； painting， scribbling（涂鸦） and making things； Sand and water play； toys for imaginative and pretending play； the first social games for learning to play and get on with others.

　　We learn from the passage that a child has boundless curiosity______.

　　A.when he is two.

　　B.when he is around four.

　　C.when he is six.

　　D.when he is eight.