Identify the adjective in the following sentence: 

It was bold of you to assume that I would not come.

Option D is the correct option. "Bold" is an adjective. Adjectives are a part of parts of speech. An adjective is a word that is used to add something to the meaning of the noun or pronoun. Adjective add quality, quantity, number, demonstration, etc to the noun or pronoun. It states the being of noun or pronoun. They can describe or modify the meaning of the noun or pronoun.