A transformation experiment

Suppose you have two strains that are trpB-. Call one of them trpB1- and the other trpB2-.

In one plate (plate #1) without tryptophan, combine trpB1- mutant cells with DNA from trpA- cells.

In another plate (plate #2) without trptophan, combine trpB1- mutant cells with DNA from trpB2- cells.

You notice that in Plate #1 with trpB1- and trpA- that there are colonies growing.

How many colonies would you expect for Plate #2?

a. there would be no colonies at all
b. there would be some colonies, but less than the number in the experiment with trpA- DNA.
c. there would be about the same number of colonies as the experiment with trpA- DNA.
d. there would be many more colonies compared to the experiment with trpA- DNA.