A student pulls horizontally on two different ideal springs, X and Y, using identical magnitudes of force. Spring X stretches 2.0cm, while spring Y stretches 3.0cm. Which statement best compares the stiffness of the two springs?
a) Spring Y is stiffer than Spring X because it stores more elastic potential energy when stretched by the same force.
b) Both springs have identical stiffness because the pulling forces are identical.
c) Spring X is stiffer than Spring Y because a smaller extension results from the same applied force.
d) Spring X is less stiff than Spring Y because stiffness is proportional to extension for a given force.