MasteringGenetics Chapter 6.2 due tonight!!

Hello!

So I've been trying to figure these last two questions out for a couple of days now, I've emailed my TA, Googled and tried EVERYTHING but I still don't understand it.

Question H: This question asks to rank the genes in the order of their transfer (screenshot attached) but I don't know which plate refers to which gene!

Here's more information should you need it:

An Hfr strain with the genotype cys+ leu+ met+ strS is mated with an F− strain carrying the genotype cys− leu −met− strR . In an interrupted mating experiment, small samples of the conjugating bacteria are withdrawn every 3 minutes for 30 minutes. The withdrawn cells are shaken vigorously to stop conjugation and then placed on three different selection media, composed as follows:
Medium 1: Minimal medium plus leucine, methionine, and streptomycin (Cys = donor)
Medium 2: Minimal medium plus cysteine, methionine, and streptomycin (Leu = donor)
Medium 3: Minimal medium plus cysteine, leucine, and streptomycin (Met = donor)

Part I
Suppose a fourth selection medium containing leucine and streptomycin is prepared. At what sampling time do you expect the first-growing colonies to appear?
sampling time = ___ min

If you can help I would really appreciate it!!