In this relationship reasoning question on family terms, select the odd word pair from the following alternatives: Sister – Brother, Son – Friend, Father – Daughter and Mother – Son.

Introduction / Context:
This verbal reasoning question deals with basic family relationships. You are given four word pairs: Sister – Brother, Son – Friend, Father – Daughter and Mother – Son. Three of these pairs represent close blood relations within a family, while one pair mixes a family relation with a non family relation. Your job is to identify which pair does not belong with the others.

Given Data / Assumptions:

• Word pairs: Sister – Brother, Son – Friend, Father – Daughter, Mother – Son.
• Sister, Brother, Son, Father, Daughter and Mother are all direct family relation terms.
• Friend is a social relation, not a blood relation.
• Exactly one pair does not represent a pure family relationship between both words.

Concept / Approach:
The key idea is to classify each pair based on whether both words describe direct family members related to each other by blood. In three of the pairs, both terms belong to the set of close family relations such as parent and child or siblings. In one pair, however, one term is a family relation and the other is a social relation that is chosen rather than inherited. That mixed pair is the odd one out.

Step-by-Step Solution:
Step 1: Analyze Sister – Brother.Sister and Brother are siblings. Both terms represent children of the same parents, making this a pure blood relationship pair.Step 2: Analyze Father – Daughter.Father and Daughter form a direct parent child relationship. Again, both are family relations.Step 3: Analyze Mother – Son.Mother and Son also form a direct parent child relationship; both words clearly describe family members.Step 4: Analyze Son – Friend.Son is a family relation, but Friend is a non family social relation. The two words do not describe two family members related to each other by blood.Step 5: Identify the odd pair.Son – Friend is the only pair that combines a family relation with a non family relation, so it is the odd one out.

Verification / Alternative check:
You can check by asking whether both words in the pair will appear on a basic family tree. Sister, Brother, Father, Daughter, Mother and Son are standard positions on a family tree. Friend, however, does not appear as a blood relation on a family diagram. Therefore, any pair containing Friend will naturally differ from the pairs composed entirely of family relation terms. This confirms that Son – Friend is structurally different from the other three options.

Why Other Options Are Wrong:
Sister – Brother: Both are siblings and form a direct family relation pair.
Father – Daughter: A clear parent child relationship within the family.
Mother – Son: Another direct parent child relationship, fully within the family network.

Common Pitfalls:
Some test takers may focus on gender differences or generational differences and get confused. However, the important classification here is not about same generation versus different generation, but about whether each pair consists entirely of family relations. When solving odd one out questions, always first group items by their broad category, such as family versus non family, before considering finer distinctions.

Final Answer:
The odd word pair is Son – Friend, because it combines a family relation with a non family relation, while the other three pairs represent pure family relationships between the two terms.