Find the odd relation (family vs non-family): Select the one that is not an immediate family relation.

Introduction / Context:
Kinship terms distinguish biological/legally defined family from social relations. Three options are immediate family members; “friend” is a social relation outside the family tree.

Given Data / Assumptions:

• Father/Mother/Brother: immediate family terms.
• Friend: non-kin social relationship.

Concept / Approach:
Classify by kinship. Immediate family membership yields inheritance and guardianship implications that friendships do not have.

Step-by-Step Solution:

Verification / Alternative check:
Check family tree diagrams: friend is external to the tree.

Why Other Options Are Wrong:
They are core family relations and thus coherent.

Common Pitfalls:
Emotional closeness does not convert a friend into kin in classification tasks.

Final Answer:
Friend