Its really a bad question.
They said that the wire has very low resistance so we neglect the effect of resistance in this case. So what they look for is your understanding of the motor effect here (it even said "a particular experiment") and how with very low resistance it is assumed that the thickness of the wire has no effect on the current produced.
In real life, this is a terrible question and as an engineer I would be more inclined to test each variable out separately by an elimination process of testing as it varies a lot in different conditions with each of those conditions in a, b, c and d.