Work Step by Step
Because the A and B genes are only 10 cM apart, the Mendelian result is not expected to occur. That result would be 25 AB: 25 ab: 25Ab: 25 aB. The linkage would be broken about 10% of the time, so Ab and aB phenotype should occur about 10% of the time when added together. That is what D. says, with all of the other answer choices contradicting that. B. and C. should have a total of 100, not 20 and 90, respectively, and A. is the answer which would be true if the genes were not linked.