You pull on a spring in two steps. the spring obeys hooke’s law. in step 1of pulling, you extend it by a distance xs. in step 2, you further extend it by the same distance xs. choose the answer that correctly compares the elastic potential energy of the spring after the first step (us1) with that after the second step (us2.) assume that the spring is initially undeformed.(a) us2> 2us1 because the average force exerted on the spring in step 2 is larger than the average force exerted on the spring in step 1.(b) us2=2us1 because the force exerted on the spring at the end of step 2 is two times larger than at the end of step 1.(c) us2> 2us1 because the more the spring is stretched, the larger the additional force that is needed to extend the spring for an additional unit distance.(d) us2=2us1 because the extension of the spring at the end of step 2 is two times larger than the extension of the spring at the end of step 1.