B.
答案错了
Tom is the tallest in his class.= Tom is taller than any other student in his class.
= Tom is taller than other students in his class.请问A为什么错了呢？student是单数名词，any只能修饰复数名词或者不可数名词。你的答案都非常对，但他们说不选A的原因是Tom也包含在student中，而B是Tom不包括student中