He is taller than the other ____ in the class.A.boy B.boys.

选B
根据句意和和后面的in the class
.the other指两个人或物中的一个时,只能用the other,不能用another,此时的other作代词.如：
He has two daughters.One is a nurse,the other is a worker.
他有两个女儿,一个是护士,另一个是工人.
the other后可加单数名词,也可加复数名词,此时的other作形容词.如：
On the other side of the street,there is a tall tree.
在街道的另一边,有一棵大树.
Mary is much taller than the other girls.
玛丽比其他的女孩高得多.
He lives on the other side of the river.
他住在河的对岸.