http://zhidao.baidu.com/link?url=sqLffaze8Mf_aBJZ95kAQILzEQ6CM80KVBabivPZZsvViNPwEWMI4mq3Np7ZGlABWw3ZA48YOJsF1UJmR9_Z6ODRdUlU1F4ENC4fzAGbbXS请解释一下选项C,如果对的话,那B1=B2了 ,怎么还会是等位基因呢