Answer:
Explanation:
1. The largest possible map distance is 50, it represents that  two genes are found at opposite ends of a chromosome or are 50 cM apart from each other or they are found on different chromosomes .
2. Genes found at opposite ends of a chromosome behave as if they are on different chromosomes.
3. As given A-B 50%, means  that recombination frequency is 50%.
The recombination frequency(RF), 50% means that either two genes are located on different chromosomes inheriting independently or  when they are widely separated on the same chromosome with far distance. Â
4. As  given here, four genes named A, B, C,  and D are known to be located on the same chromosome. so A-B are 50 cM or more  far  apart from each other.