Why is the answer C Using P22 as a generalized transducing p

Why is the answer C?

Using P22 as a generalized transducing phage grown on a gal^+leu^+ arg^+ bacterial donor, a recipient strain of genotype gal^-leu^- arg^- is infected and incubated. What medium would select for arg^+ transductants? Minimal medium Minimal medium + arginine Minimal medium + leucine Minimal medium + galactose + leucine Minimal medium + leucine + arginine Minimal medium + galactose + leucine + arginine Cannot determine

Solution

Answer