The correct answer is B.
The stability factor of a transistor is a measure of its resistance to changes in collector current due to changes in base current. A higher stability factor indicates that the transistor is more resistant to these changes.
In this case, the stability factor is 50. This means that if the base current changes by 1 µA, the collector current will change by 50 µA.
Therefore, if due to temperature change, ICBO changes by 1 µA, then IC will change by 50 µA.
Option A is incorrect because it is twice the value of the stability factor.
Option C is incorrect because it is half the value of the stability factor.
Option D is incorrect because it is the value of the stability factor.