Answer:
As it is not stated which word is it (not underlined), I'll go ahead and give you the answer for each one of your options:
A. Pronoun: There aren't any pronouns in this sentence.
B. Noun: People, top monument
C. Verb: climb
D.Adjective: Top.
Explanation:
A pronoun can be: I, you, he, she, etc... A noun is an object or a thing. A verb is an action, in this case climb is the action of this sentence. And and adjective is a description word, top is describing the noun, which is the monument. Top can also be used as a noun, depending on the context.
