Yes you are right as from the phase diagram it can be seen :
A. Substance X is in the solid phase in the area shown by “1”.
B. Substance X exists as a solid, a liquid and a gas at point D.
D. Substance X is a liquid in the area shown by "2"
But the point C is not correct as Substance X is not undergoing a change from a liquid to a gas at the line shown by E while it undergoes a phase change from solid to gas.