Doubling Only the Spring Constant of a Vibrating Mass-And-Spring System

Multiple Choice

Doubling only the spring constant of a vibrating mass-and-spring system produces what effect on the system's mechanical energy?

A) increases the energy by a factor of square root of two
B) increases the energy by a factor of two
C) increases the energy by a factor of three
D) increases he energy by a factor of four
E) produces no change