Thats pretty much it. Simple really.
If you go back to basics, the 4 forces in balanced flight are:
weight = lift and (importantly for these curves) thrust = drag.
Now, looking at things like that, we can see that drag is, by definition, the amount of thrust required in order for them to cancel out.
They are just two names for the same thing. Q41 is just really seeing if you understand this. Another way of writing the same Q is to say:
on a drag curve, what is the speed for minimum drag. Answer, Vmd.
Yes?