Answer:
C: whatever is making that noise
Explanation:
A noun clause is a group of words that describes the subject in the sentence. There is a subject and a verb in a noun clause.
Noun clauses are used in the place of a noun that can either be a subject, object or compliment in the sentence.
In the given sentence the noun clause is 'whatever is making that noise'.
Here, the noun clause is acting as the indirect object of the verb 'find'. 'Find' is the verb in the independent clause 'I have to find'.
