In this family relationship reasoning question, select the one term that does not belong to the group: Niece, Nephew, Aunt and Sister.

Introduction / Context:
Odd man out questions based on family relationships test your understanding of how different relatives are classified, often by gender or generation. In this problem, four relationship terms are given. Three of them share a common property and one is different. Such questions are common in verbal reasoning and general intelligence sections of competitive exams because they check both vocabulary and logical grouping.

Given Data / Assumptions:

• The four options are: Niece, Nephew, Aunt and Sister.
• All four are close family relation terms used in everyday language.
• We use standard meanings: niece and nephew are children of a sibling, aunt is a sister of a parent, and sister is a female sibling.

Concept / Approach:
One clean way to classify these words is by gender. Reasoning questions often form a group where three items refer to one gender while the fourth refers to the other gender. Here we check whether each term refers to a male or female relative. Once that is clear, the term with different gender from the majority will be the odd one out.

Step-by-Step Solution:
Step 1: A niece is the daughter of one's brother or sister, so niece is always a female relative. Step 2: An aunt is the sister of one's father or mother, or the wife of one's uncle, so the term aunt also clearly refers to a female relative. Step 3: A sister is a female sibling, so this word again refers only to a female person. Step 4: A nephew is the son of one's brother or sister, which makes the nephew a male relative. Step 5: Thus, niece, aunt and sister are female relatives, while nephew is a male relative. This makes nephew the odd one out.

Verification / Alternative check:
We can double check by thinking of sample sentences. We say “She is my niece”, “She is my aunt” and “She is my sister”, and in each case the pronoun she fits naturally, which confirms they are female. For nephew, we say “He is my nephew”, and the pronoun he is correct. Therefore, nephew differs in gender from the other three terms and must be the odd item out.

Why Other Options Are Wrong:
Niece is wrong as the odd one out because it matches the female gender property shared with aunt and sister. Aunt is wrong as the odd one out because it is also a female relative, consistent with niece and sister. Sister is wrong as the odd one out because it is again clearly a female relation, not unique among the group.

Common Pitfalls:
Some students may get distracted by generational differences, noting that a niece and nephew belong to a younger generation, aunt belongs to an older generation, and sister belongs to the same generation. However, this does not create a clear majority property to isolate one term. Focusing on gender produces a simple and unique pattern, which is usually what exam setters intend in such questions.

Final Answer:
The only male relation among the four options, and therefore the odd one out, is Nephew.