Odd man out:

Concept: In an ‘odd one out’ classification set, three items share a common defining category (here, a taxonomic animal family), while the outlier belongs to a different category altogether.

Application: Leopard, cougar, and lion are all members of the cat family, Felidae — carnivorous mammals sharing traits such as retractable claws, forward-facing eyes, and a build suited to stalking prey.

Contrast (each option by value):

• Leopard is a Felidae member (a big cat), matching the shared category.

• Cougar (also called the mountain lion) is a Felidae member too, fitting the same classification.

• Lion is a classic Felidae member, matching the other two cats.

• Elephant belongs to a completely different order, Proboscidea — it lacks the claws, dentition, and body plan common to the cat family.

Result: Elephant is the only animal here that is not part of the cat family, so it is the odd one out.