Which preposition completes the given sentence?

A preposition is a word or expression that associates a thing or pronoun to an action word or modifier in a sentence. In certain dialects, it is a connection such as in, by, for, with, to, and lots more, that associates a lexical word, generally a thing or pronoun, or a syntactic development, to another component of the sentence, concerning an action word, thing, or a descriptor.

However, the preposition which completes the sentence is after rapidly perusing the total thought; we recognize the connector that. This is the central purpose of the entire thought. Following the connector, we have a total sentence that starts with it.

The word that precedes the connector is, and this is the fundamental connecting action word of the total thought. Hence, we can securely foresee a sort of expression which links benefit to study.

Of-after quickly reading the complete idea, we identify the connector that. this is the middle point of the whole idea. after the connector we have a complete sentence that starts with it. the word before the connector is is and this is the main linking verb of the complete idea. therefore, we can safely anticipate a kind of phrase which connects benefit to study. it is not letter d since it is a connector for reason. it is not letter c since we already have this connector. it is not letter b since it is the same type of connector as letter c. the correct answer is a.