Select the Venn diagram that best illustrates the relationship between the…

Concept — In a logical Venn diagram every class is drawn as a circle, and the way the circles sit states the relationship between the classes. A circle drawn wholly within another says that every member of the inner class is also a member of the outer class. Circles that cross say the two classes share some members but neither one holds all of the other. Circles drawn apart say the two classes have no member in common.

Applying it here —

1. Every alligator is a reptile, so the class of alligators sits wholly within the class of reptiles.

2. Every reptile is an animal, so the class of reptiles sits wholly within the class of animals.

3. Chaining the two subset links gives alligators within reptiles within animals, so the three classes need three circles drawn one within the next: animals as the outermost circle, reptiles within it, and alligators as the innermost circle.

Cross-check against the other arrangements —

• Two crossing circles beside a separate circle would say that some alligators are not reptiles and that a third class has no member in common with either; both readings are false here.

• Two separate circles drawn inside one larger circle without meeting would say that no alligator is a reptile, which contradicts the fact that alligators are one kind of reptile.

• One circle within another beside a separate circle records just one of the two subset links and leaves the remaining class unrelated, but animals hold reptiles, so no class here stands apart.

Result — the required drawing is the fully nested one: the smallest circle (alligators) within the middle circle (reptiles), and that pair within the largest circle (animals).