This is a physics problem related to the mechanical energy of a block-spring system. The block is initially at rest against a compressed horizontal spring, which means the system has a certain mechanical energy at time $t_0$. When the block is released, it moves along a track, and the energy of the system changes by time $t_1$.

The question asks about the relationship between the mechanical energy at times $t_0$ and $t_1$. Friction is negligible, so we can assume that the total mechanical energy is conserved, except for any potential changes in the spring’s stored energy or kinetic energy of the block.

Let’s go over the options:

• Option A: $E_1 < E_0$ — This suggests that the energy decreases, which isn't likely without energy loss mechanisms (like friction or a non-conservative force).
• Option B: $E_1 = E_0$ — This suggests that the mechanical energy is conserved, which makes sense in the absence of friction.
• Option C: $E_1 > (E_0 = 0)$ — This is incorrect because $E_0$ cannot be zero when the block is compressed against the spring.
• Option D: $E_1 > E_0 > 0$ — This also suggests an increase in mechanical energy, which doesn’t fit because there's no energy input, only energy conversion (spring potential energy to kinetic energy).

The correct answer is most likely Option B: $E_1 = E_0$, as mechanical energy is conserved in this system.

Would you like a more detailed explanation of how energy conservation applies to this scenario, or is there another part of the problem you'd like help with?