A block of mass m on a horizontal surface is attached to one end of a horizontal spring. The other end of the spring is fixed. The block oscillates with negligible friction and an amplitude of 4.0 cm. How far from the equilibrium position is the block when the kinetic energy of the block is three times the potential energy of the system?
A) 1cm
B) square root of 2 cm
C) 2 cm
D) 2(square root of 2) cm
E) 3 cm