Which word is a singular noun?
a. athlete
b. men
c. clowns
d. dancers

D). Athlete.

Explanation:

The noun is described as the part of speech that is employed to define or name an object, person, or place. It aids to identify or represent a place or a thing or a class of people. Noun has been categorized into several types depending on the context. One of this categorization includes, division based on number into singular and plural.

As per the question, the word 'athlete' could be treated as singular as it alludes to a single person(athlete). Thus, option A would be the answer as the other options(men, clowns, dancers in options B, C, and D) are referring to more than one(plural) noun.