Which of the following parts of speech is most often used with a noun to create a descriptive phrase?

A. pronoun
B. preposition
C. adverb
D. conjunction

C is incorrect.

B. preposition is most often used with a noun to create a descriptive phrase.

The part of speech that is most often used with a noun to create a descriptive phrase is the adjective. To identify the correct answer among the options you provided, we need to understand the function of each part of speech in relation to a noun.

A. Pronouns are typically used to replace nouns, not to describe them. For example, instead of saying "the big cat," we might say "it" or "the animal."

B. Prepositions are words that show a relationship between a noun or pronoun and other words in a sentence. While prepositional phrases can provide additional information about a noun, they do not directly describe the noun. For example, in the phrase "the cat on the rug," the prepositional phrase "on the rug" tells us where the cat is, but it doesn't describe the cat itself.

C. Adverbs modify verbs, adjectives, or other adverbs. They do not typically describe nouns directly. For example, in the sentence "The cat quickly ran," the adverb "quickly" modifies the verb "ran," not the noun "cat."

D. Conjunctions are used to join words, phrases, or clauses together, but they are not used to directly describe nouns.

Therefore, the correct answer is A. Adjective, as it is the part of speech most commonly used to describe nouns.