For A.), B.) and C.)

In case of intrinsic semiconductor, it will always be the case that the electrons will flow to the positive terminal and holes to the negative terminal polarity because the holes and electrons are uniformly distributed. And similar would be the case for both types of semiconductor.

For D.)

In p-n junction, when the p-side is connected in forward bias, the depletion region decreases and the charge carriers are able to diffuse and a diffusion current is produced. But when the polarity is reversed, the depletion region increases, which decreases the diffusion current. Therefore, the current in p-n junction only flows in forward biasing and reduces to zero in reverse biasing.