Certainly a > b must hold, oth. you wont enter the if.
weakest (least restrictive) condition among the choices thus
with (x = a) or (a > b) you enter the if.
Don't mind why x = a, or x = sth else, or sth else = sth else.
The important thing here is (a > b) and any stupid thing ORed with it.
I hate those questions by the way. You will try one by one and hope
you will not miss anything.