Ionic is the answer. Hope this helps!
You need to do your own work honestly.
Genes B and C with 10% recombination frequency are closest to each other. Because recombination happens at random, the distance between genes that are farther from each other creates higher recombination frequency. A low recombination frequency of 10% means the genes are closest to each other. The short distance between the two genes allow fewer recombination to happen, thus the frequency is low.