Interference occurs when: A. two genes are far apart on a genetic map. B. a crossover causes the termination of the meiosis event in which the crossover is occurring. C. the number of recombinant progeny classes in the testcross of a heterozygote exceeds the number of parental progeny. D. one crossover inhibits another. E. two genes are assorting independently

The correct answer is D. one crossover inhibits another.

Explanation:

In genetics, interference is defined as a reduction or an increase in the chances of occurrence of further crossover event in a given interval at one location or a close by region of the chromosome, due to crossover occurring in another location.

Succinctly, interference occurs when one crossover inhibits another.