Chemistry · Structure of atom

In a hydrogen atom, which of the following transitions or states corresponds to the ground state energy of the electron?

1. A
   When the electron is in 2s orbital
2. B
   When the electron is in an excited state with principal quantum number n > 1
3. C
   When the electron resides in 1s orbital, corresponding to the most stable condition
4. D
   When the orbitals have degenerate energies