The correct option is A True
Noun clauses can begin with 'that', 'if', 'whether' and so on. The question "Would she have gone ahead with the rash decision?" which when combined with "We didn't know" becomes a statement. Hence 'if' is incorporated into the sentence. The clause, "if she would have... ." is a noun clause that is also the subordinate clause here (because it does not express a complete thought). Hence the statement is true.
Using this explanation, option A is correct and B is incorrect.