Concept:The depletion region is the charge-free zone at a p-n junction, and its width depends on the biasing direction.
Explanation:In reverse bias, the p-side is connected to the negative terminal and the n-side to the positive terminal of the battery.
Holes in the p-region are pulled away from the junction, and electrons in the n-region are also pulled away.
This makes the junction region more depleted of free charge carriers.
Therefore, the width of the depletion region increases in reverse bias.
In forward bias, charge carriers move toward the junction and neutralise the depletion region, so its width decreases.
Hence, the depletion region of a p-n junction increases only when it is reverse biased.
Answer:Option A: increases if reverse biased.