Final answer:
An antibonding π orbital can hold a maximum of 2 electrons, according to the principles of molecular orbital theory.
Step-by-step explanation:
An antibonding π orbital can contain a maximum of two electrons. According to the principles of molecular orbital theory, each molecular orbital, whether it is a bonding or antibonding orbital, can hold up to two electrons, just as atomic orbitals do. This rule is similar to the one explained in the electron configuration for atoms, where each orbital can be occupied by a maximum of two electrons with opposite spins. Therefore, the correct answer to the question is (b) 2 electrons.