(Problem 19) Two mutations that affect plaque morphology in
phages (a– and b–) have been isolated. Phages carrying both
mutations (a– b–) are mixed with wild-type phages (a+ b+) and added
to a culture of bacterial cells. Subsequent to infection and lysis,
samples of the phage lysate are collected and cultured on bacterial
cells. The following numbers of plaques are observed: What is the
frequency of recombination between the a and b genes?

A. 42%

B. 44%

C. 14%

D. 7%

E. 0%