题目

As we all know, bikes are mainly made of steel(钢材). But can you imagine that they can be made of bamboo? Do you want to know how a bamboo bike is produced? Do you want to make your own bike with bamboo? You can do it at the Bamboo Bike Studio(工作室) in New York. People there can teach you how to make your own bamboo bike.  The studio is also helping build factories in Ghana(加纳), which is a country in western Africa. The factories will make cheap bamboo bikes. Bamboo is as good as steel for building a good bike. Marty Odlin works at the studio. He says a bamboo bike is the wo某人成年后，身体仍不足1米，而且智力低下，很可能是幼年时期体内缺乏下列哪一种物质所致A．胰岛素B．甲状腺激素C．性激素D．生长激素