Which of these is not a part of speech?

question 1 options:

preposition

interjection

conjunction

none of the above

Grammar - Parts of Speech - Conjunctions. A conjunction is a word that connects other words or groups of words. In the sentence Bob and Dan are friends the conjunction and connects two nouns and in the sentence He will drive or fly, the conjunction or connects two verbs.

A preposition connects the relationship between a noun, pronoun and phrase to other parts of the sentence. Whatever object or phrase the preposition is introducing is called the object of the preposition. Each bold word in the following sentences are examples of prepositions: The box is on the desk.

Some grammarians believe that interjections are the least important part of speech. This is because interjections are not generally required in order for the meaning of a sentence to become clear. An interjection is a word solely designed to convey emotion. It expresses meaning or feeling.
 
I think its none of the above

Personally i think it is a

The answer would be d, coherence.