The concept here revolves around the structure of hydrogen atom energy levels and how electrons move between these levels by absorbing or emitting photons. Importantly, all the options given (1s, 2s, 2p, and 3s) are valid electronic levels for a hydrogen atom. However, the key lies in understanding the process of absorption and emission of photons in relation to these levels.

In a hydrogen atom, when an electron moves from a lower energy level to a higher energy level, it absorbs a specific amount of energy, which is taken in as a photon. Conversely, when an electron drops from a higher energy level to a lower energy level, it emits a photon, releasing the previously absorbed energy.

For an electronic level to allow the hydrogen atom to absorb a photon but not to emit a photon, the concept itself is somewhat misleading because any excited state (above the ground state) has the potential both to absorb (moving to an even higher level) and to emit photons (returning to a lower energy state). However, considering the question's framing, we can interpret it as looking for a level that fundamentally represents the ground state or a state from which no photon emission would occur without first absorbing energy to reach an excited state.

Given the options: - 1s (Option D): This is the ground state of a hydrogen atom, the lowest energy level. - 2s and 2p (Option B and C): These are excited states above the ground state. - 3s (Option A): This is a further excited state above 2s and 2p.

Therefore, Option D (1s) is the only level from which the atom cannot emit a photon without first absorbing energy because it is the ground state. In any other state (2s, 2p, 3s), the atom can both absorb a photon to move to a higher state and emit a photon when it transitions back to a lower energy level, including the 1s level.