Question

>
stick to what you promised to do. (pick out
the a subordinat noun clause)​

Answer 1

A subordinate clause which acts as a noun in a sentence is called a Noun Clause. It usually starts with words such as 'that, what, whatever, who, whom, whoever, whomever'. It acts exactly like a noun in a sentence. It can work as a noun either at the place of a subject or an object.

So question = Stick to what you promised to do.

Answer = What

Hope it helps!!