5. Two blocks are at rest on a frictionless, level table. Both blocks have the same mass m, connected by a spring of negligible mass. The separation distance when the spring is relaxed is L. During a time interval Δt, a constant force F is applied horizontally to the left block, moving it through a distance x₁. The right block moves through a distance x₂. When the force F is removed, what is the total energy of the system associated with vibration relative to its center of mass?

(A)
(B)
(C)
(D)
(E) It cannot be determined