An atom of mass m, initially at rest, resonantly absorbs a photon. It makes a transition from the ground state to an excited state and also gets a momentum kick. If the difference between the energies of the ground state and the excited state is ℏΔ, the angular frequency of the absorbed photon is closest to:

1. Δ (1 + 3/2 ℏΔ / (mc²)
2. Δ (1 + 1/2 ℏΔ / (mc²)
3. Δ (1 + ℏΔ / (mc²)
4. Δ (1 + 2 ℏΔ / (mc²)