Answer
D
Work Step by Step
By observing how often crossovers happen (recombination rates), we can determine how close or far genes lie on a chromosome in relation to one another. More crossovers (higher recombination rates) mean that two genes lie far away from each other on the chromosome. We would then expect that two genes that lie close to one another on a chromosome would not cross over as much. In this way, a gene map can be constructed.
