The phenomenon in which one crossover decreases the likelihood of crossovers in nearby regions is called

b. negative interference

Explanation:

Interference is defined as the degree to which one crossover interferes with the other additional crossovers in the same region.

Interference is 1 which is coefficient of coincidence.

The ratio of observed double cross overs to expected double crossovers is referred to as the coefficient of coincidence.

Interference can either positive or negative.

It is said to be positive value when there are fewer number of observed double crossovers than expected form the single crossover frequencies. This only indicates that a crossover interferes with a second crossover nearby.

While on the hand a negative interference is when more double crossovers occur than expected. This suggests that a crossover event can stimulate additional cross over evens in the same region of the chromosome.