Time-of-entry experiments indicate that a gene for resistance to kanamycin, kan-r, is closely linked to a gene for resistance to bacteriophage T5, T5-r. A geneticist has strains of two genotypes available, kan-r T5-s (resistant to kanamycin, sensitive to phage T5) and kan-s T5-r (sensitive to kanamycin, resistant to phage T5). In an experiment using phage P1 to learn whether the genes are close enough for cotransduction, how would the experiment be done:

A) Which strain would you infect with the P1 to obtain the transducing phage?

B) Which strain would you infect with the transducing phage?

C) Which marker would you select to obtain transductants?

D) How would you determine whether the genes were cotransduced?