When a p-n junction is reverse biased, then the depletion region of the junction is

Explanation

When a p-n junction is reverse biased, the electric field across the junction increases, causing the depletion region to widen. This occurs because the external voltage causes more charge carriers to be swept out of the junction area, increasing the width of the region where no charge carriers are present. As a result, option B is correct. Option A is incorrect because the depletion region cannot become zero in reverse bias. Option C is incorrect because the depletion region actually widens, not narrows. Option D is incorrect because the depletion region does change size when reverse biased; it does not remain unchanged.