Two blocks $X$ and $Y$ rest on a horizontal frictionless surface. Block $Y$ has a greater mass than block $X$. A spring is attached to one end of block $Y$. The blocks are pressed together so that the spring is compressed between them, and they are kept stationary as illustrated. When they are released, the blocks travel in opposite directions. Which of the following statements is correct?
- AAfter release, the kinetic energy of block $X$ must equal the kinetic energy of block $Y$.
- BAfter release, the sum of the kinetic energies of the blocks is equal to zero.
- CThe total energy of the spring and blocks immediately before release is zero.
- DThe total energy of the spring and blocks is equal to the energy needed to bring the blocks together.