The correct answer is B. Decreased.
BJT gain is the ratio of the collector current to the base current. When the gain is high, a small change in the base current can cause a large change in the collector current. This can lead to latch-up, which is a condition where the transistor is turned on and cannot be turned off. To avoid latch-up, the gain of the transistor should be decreased.
Option A is incorrect because increasing the gain will increase the risk of latch-up.
Option C is incorrect because maintaining the gain constant will not prevent latch-up.
Option D is incorrect because changing the gain randomly will not prevent latch-up.
Latch-up is a serious problem that can damage the transistor and other components in the circuit. It is important to take steps to avoid latch-up, such as decreasing the gain of the transistor.