Identify the correct increasing order of energies of molecular orbitals for the $F_2$ molecule.

• A
  $\sigma 1s < \sigma^* 1s < \sigma 2s < \sigma^* 2s$
• B
  $\sigma 1s < \sigma^* 1s < \sigma^* 2s < \sigma 2s$
• C
  $\sigma^* 1s < \sigma 1s < \sigma 2s < \sigma^* 2s$
• D
  $\sigma 1s < \sigma 2s < \sigma^* 1s < \sigma^* 2s$