Question

Modify the noun clause into a noun phrase:
You don't know why he behaved the way he did. [Advanced]

• A. the reason behind his behaviour
• B. him as well as I do
• C. why his behaviour was like this
• D. none of the above

Answer 1

The correct option is A the reason behind his behaviour

A noun clause is a dependent clause that functions as a noun. It usually begins with what, whatever, whom, that and other such relative pronouns. A noun clause can act as a subject, object, predicate nominative or object of a preposition, in a sentence.
A noun phrase is a word or a group of words containing a noun, that functions as the subject, object or object of a preposition in a sentence. A phrase does not contain a subject or a verb, or both of them (as opposed to a clause).
In option A, the question word 'why' is removed and the verb 'behaved' is changed to a noun 'behaviour'. It is the most suitable noun phrase that is equivalent in meaning to the underlined clause. Hence option A is correct.
Option B is incorrect because it is different in meaning from the underlined clause.
Option C is incorrect because it is still a clause, with the subject 'his behaviour' and the verb 'was'.
Option D is incorrect because the answer lies in A.