Choose the word which is different from the rest.

Mother
Friend
Sister
Father E. Brother

The answer is B. Friend.

A, C, D, and E are all family members. A mother is a female parent. A sister is a female sibling. A father is a male parent. A brother is a male sibling. A friend is a person who you like and spend time with, but is not related to you.

In this case, the word “friend” is different from the rest because it is the only word that does not refer to a family member.