Identify the diagram that best represents the relationship among classes given…

Concept

A Venn (logic) diagram shows how categories relate by how their circles overlap. Two categories that can never share a member are drawn as separate, non-touching circles (disjoint); a category whose members can also belong to a second category is drawn so the two circles overlap; and a category fully inside another means every one of its members belongs to the larger one.

Application

Test each pair among Boy, Girl and Student:

• Boy and Girl: no person is both a boy and a girl, so these two categories share no member — their circles must be separate (disjoint).

• Student and Boy: some students are boys (and some boys are not students), so these two circles must partly overlap.

• Student and Girl: some students are girls (and some girls are not students), so these two circles must partly overlap as well.

So the matching diagram has two non-touching circles (Boy and Girl) that each overlap a third, central circle (Student), while Boy and Girl never touch each other — the row of three circles in which the middle circle overlaps each of the outer two, and the two outer circles stay apart.

Cross-check

Three fully separate circles would wrongly say no student is a boy or a girl. Three concentric circles (one inside another inside another) would wrongly say every boy is a girl and every girl is a student. A small circle inside a large one with a third circle apart would wrongly make one category a complete subset and leave a category sharing nothing — none of these fits all three real relationships, so they are rejected.