Select the sentence that uses a noun clause to combine the ideas below.

Water aids digestion. It is really true.

That water aids digestion is really true.

Water aids digestion; it's really true.

It is really true where water aids digestion.

Water that aids digestion is really true.

That water aids digestion is really true.

Explanation:

Defining and Identifying a Noun Clause:

A noun clause always starts pronouns like how, that, what, whatever, when, where, whether, which, whichever, who, whoever, whom, whomever, and why etc. to support the noun in the sentence. Noun clauses represent subjects and objects both direct and indirect.

That water aid digestion is the predicate of the sentence with the subject in it. Predicate is that part of a sentence or a clause which tells us about the role of noun. In the middle of predicate is the verb. Along with verb a predicate contain the subject of the sentence in it.

A noun clause is a combination of words with having a subject and a verb that don't give complete thought when used alone. This sentence contains a noun clause. Subject in this sentence is Water, "That" is the pronoun (supporting the noun in the sentence) and aid is verb.