What type of word indicates a noun will soon follow?
a. article
b. adjective
c. pronoun
d. preposition

The right answer is the pronoun

A pronoun is a name that replaces a noun, an adjective or a proposition.

A pronoun is a small word that avoids the repetition of a noun or - in some cases - an expression or proposition. It thus replaces a noun or segment already mentioned (the antecedent), and agrees with its antecedent. The pronoun refers to its logical antecedent in the sentence or in the human context. In the sentence, the logical antecedent is most often the preceding noun.

and your question what topic are you in trouble with?