If we observe an object moving in one dimension at constant velocity, what does that imply about the forces that are acting on that body? How does your answer change if that constant velocity is zero?

a) Net force is zero; no change in answer if velocity is zero
b) Net force is zero; answer changes if velocity is zero
c) Net force is not zero; no change in answer if velocity is zero
d) Net force is not zero; answer changes if velocity is zero