The correct answer is B. 3.00%.
Annually increasing flexible premiums are a type of life insurance policy that allows the policyholder to increase their premium each year. This can be done to keep up with inflation or to increase the death benefit. The rate of increase is generally 3%, but it can vary depending on the insurance company.
Option A, 2.50%, is a lower rate of increase than is typically used for annually increasing flexible premiums. This rate may be used by some insurance companies, but it is not the most common rate.
Option C, 5.00%, is a higher rate of increase than is typically used for annually increasing flexible premiums. This rate may be used by some insurance companies, but it is not the most common rate.
Option D, 7.50%, is a very high rate of increase. This rate is not typically used for annually increasing flexible premiums.
In conclusion, the correct answer is B. 3.00%. This is the most common rate of increase used for annually increasing flexible premiums.