In biasing of a transistor, which region must be reverse biased?

Explanation

The correct answer is Option B: Collector-base. In a transistor, the collector-base junction must be reverse biased to ensure that the majority of charge carriers are prevented from flowing from the base to the collector. This creates a high resistance barrier and is essential for the transistor to function properly. Option A is incorrect because the emitter-base junction needs to be forward biased to allow the flow of charge carriers. Option C is incorrect because there is no direct biasing of the emitter-collector junction in standard transistor operation. Option D is incorrect as it contradicts the requirement of reverse biasing the collector-base junction.