Let n_p and n_e be the numbers of holes and conduction electrons in an extrinsic semiconductor.

Extrinsic semiconductor made up by adding trivalent impurities are called p-type semiconductor. In p-type semiconductor, the number of holes is greater than number of electrons (n_p > n_e).

Extrinsic semiconductor made up by adding pentavalent impurities are called n-type semiconductor. In n-type semiconductor, the number of electrons is greater than number of holes (n_p < n_e).

However, the question does not mention which type of extrinsic semiconductor is considered. Option B is true for intrinsic semiconductor. Hence we can say that the number of electrons and holes are not equal for an extrinsic semiconductor. Therefore, the correct answer is option D.