Which graph can represent the total mechanical energy of the block-spring system as a function of x?

Question

A block oscillates without friction on the end of a spring as shown. The minimum and maximum lengths of the spring as it oscillates are, respectively, x_min and x_max. The graphs below can represent quantities associated with the oscillation as functions of the length x of the spring.

Which graph can represent the total mechanical energy of the block-spring system as a function of x? 

(A) A

(B) B

(C) C

(D) D 

(E) E

Answer 1

Correct option (E) E

Only conservative forces are acting which means mechanical energy must be conserved so it stays constant as the mass oscillates.