A Mass Is Attached to a Vertical Spring and Bobs

Multiple Choice

A mass is attached to a vertical spring and bobs up and down between points A and B. Where is the mass located when its potential energy is a minimum?

A) at either A or B
B) midway between A and B
C) one-third of the way between A and B
D) one-fourth of the way between A and B
E) none of the above