Select the sentence from the paragraph that contains a noun clause.

I know without a doubt that I should drink more water after exercising. This morning I went running, and afterward I felt tired and sick. If I drink water before and after running, I usually feel great. Next time I run, I will carry a water bottle with me.
I know without a doubt that I should drink more water after exercising.

This morning I went running, and afterward I felt tired and sick.

If I drink water before and after running, I usually feel great.

Next time I run, I will carry a water bottle with me.

A noun clause is a group of words with a subject and a verb whose function is to acts as a noun in a sentence, thus, it can be a subject, a direct or indirect object, a predicate nominative, or an object of a preposition. We can identify them because they tend to begin with the words that, how, what, whatever, when, where, whether, which, whichever, who, whoever, whom, whomever, or why.

“-that” clauses like “that I should drink more water after exercising” are often examples of noun clauses. In this case, the noun clause is acting as the direct object of the verb “know.”

Direct objects are nouns or pronouns that receive the action in the sentence; they can be identified by answering the “what?” or the “who?” questions. So, to make sure that this clause is acting as a direct object, we can ask the question “what do you know without a doubt?” The answer to this question is the direct object: “that I should drink more water after exercising.”