Final answer:
Without specific distances provided between the gene pairs, it is impossible to accurately predict which pair would have the most crossing over. The principle stands that genes farther apart on a chromosome are more likely to undergo recombination.
Step-by-step explanation:
The question relates to genetic recombination and crossing over between genes on a chromosome. In the context of the figures and information provided, crossing over is more likely to occur between genes that are farther apart on a chromosome. Therefore, the genes that are expected to have the most amount of crossing over occurring between them would be those that are the farthest apart on the linkage map. The options provided (a & c, b & c, e & f, a & e) pertain to genes on a chromosome, and without the actual distances provided in the figures, we cannot decisively determine which pair will have the most crossing over. However, the general principle is that the farther apart two genes are, the more likely they are to undergo recombination during meiosis.