Thanks, it helps a lot.
So if the y-axis value was recording torque on the coil instead, would Graph B be the most appropriate answer option or is it completely different?
torque = F perpendicular r
We've just discussed how F is behaving (& we know it's always vertical in this case), so let's look at r
r isn't AB - the armature is rotating around the dotted line and r would be .5*BC or equivalently .5*AD
the component of BC/AD which is perpendicular to F = the component of BC/AD which is horizontal
So lets define theta as the angle between the armature and the horizontal plane
(if this explanation didn't make sense let me know)
In this case, torque = Force * .5*BC*cos(theta)
As you can see, this is best represented by the graph B