Compare the energies of excitation and emission for fluorescence. which is greater and why?

The excitation energy is always greater than the emission energy .

Explanation:

When a molecule absorbs energy, electrons are excited from the ground state (S₀) to different vibrational levels of the excited state (S₁) in about 1 fs.

In the next picosecond, most of them will drop to the lowest vibrational level of S₁.

They remain there for about 10 ns, and then they drop to different vibrational levels of S₀.

The excitation energy is always greater than the emission energy because excitation occurs from the ground state of S₀ to a higher vibrational level of S₁, while emission occurs from the lowest vibrational level of S₁ to a higher vibrational of S₀.

the answer to your question is c