The main idea of a paragraph is most often
a. introduced in the first sentence.
b. introduced in the second sentence.
c. scattered throughout the paragraph.
d. introduced in the last sentence of the paragraph.

he chooses to climb mount everest and decided not to any more due to the 1,000s of people making a line on the mountion

explanation:

basic principle: a pronoun usually refers to something earlier in the text (its antecedent) and must agree in number — singular/plural — with the thing to which it refers. the indefinite pronouns anyone, anybody, everyone, everybody, someone, somebody, no one, and nobody are always singular.