The correct option is A True
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.
The noun clause "That she is going to win this contest" is the subject of the verb "is".
Hence the statement is true and option A is correct, B is incorrect.