Answer: The correct answer is :
B --- 33 ---- D
/ \
C ----- 20 ------ B-8 ---- A ---- 25 ----- D
I
C ----- 28 ------ A
Explanation: Link maps: Recombination frequencies can be used to map the relative location of genes on a chromosome. 1 map unit%. Father apart genes are, the higher the probability that a cross over will occur.