In an unbiased p-n junction, the drift current is equal to diffusion current to keep the net current equal to zero. Hence Option C is false.

The junction/barrier potential is reduced by the forward biased applied voltage and hence more holes diffuse on the n-side and more electrons diffuse on the p-side. The diffusion current is large when compared to the drift current and hence the net current is in the direction of diffusion current. Hence option A is true.

The junction/barrier potential is increased by the reverse biased applied voltage. This blocks the diffusion of holes and electrons. The drift current (in microamperes) is large when compared to the diffusion current and hence the net current is in the direction of drift current. Hence option B is false.

Therefore, the correct answer is option A.