What part of speech uses the suffix -ment?

The correct choice is a noun, as the suffix -ment is commonly used to form nouns from verbs. This suffix indicates a state, condition, or result of an action. For example, the verb "develop" can be transformed into the noun "development," which signifies the process or result of developing. This is a key characteristic of the suffix -ment, making it a clear indicator of noun formation. Understanding this usage can greatly assist in expanding vocabulary and comprehending word structures in the English language.