The correct answer is cannot determine can you please explai

The correct answer is \'cannot determine\', can you please explain why in details? I thought E was the correct answer? Thank you.

Using P22 as a generalized transducing phage grown on a leu+ arg+ a+ bacterial donor, a recipient strain of genotype leu- arg - a- is infected and incubated. What medium would select for leu+ transductants?

A. Minimal medium

B. Minimal medium + arginine

C. Minimal medium + leucine

D. Minimal medium + a + leucine

E. Minimal medium + a + arginine

F. Minimal medium + a + leucine + arginine

G. Cannot determine

Solution

Yes G is the correct answer because The order can be deduced from cotransfer rates. It is leu+ arg+ a+. The closer the two genes, the higher the rate of cotransfer. leu and arg are closest. a+ transduction requires a crossover on both sides of the leu gene. Because leu is closer to arg than a+,