The correct answer is: B. Decreasing
A parasitic PNP transistor is a type of transistor that is formed unintentionally in a semiconductor device. It can have a significant effect on the carrier lifetime in the device. The carrier lifetime is the average time that an electron or hole remains in a semiconductor before it recombines with another carrier. The parasitic PNP transistor can decrease the carrier lifetime by providing a path for carriers to recombine more quickly.
The other options are incorrect because they do not accurately describe the effect of the parasitic PNP transistor on the carrier lifetime. Option A is incorrect because the parasitic PNP transistor does not increase the carrier lifetime. Option C is incorrect because the parasitic PNP transistor does not exponentially decrease the carrier lifetime. Option D is incorrect because the parasitic PNP transistor does not exponentially increase the carrier lifetime.