When two atomic orbitals (AO) are combined to form molecular orbitals (MO), which of the following?

Question

descriptions of the energy of the resulting molecular orbitals is most accurate?

a) the MO are of lower energy than the AO

b) one MO is higher and one MO is lower than the AO

c) the MOs are of higher energy than the AO

d) the MOs are the same energy as the AO

e) none of these

Please help me with this the answer that i have is b , but why is that

Answer 1

e); AOs combine to form MOs. Half the MOs formed are bonding and the other half are nonbonding. The nonbonding MOs are of higher energy than the AOs but the bonding MOs are of lower energy than the AOs.