One Strain of RII- Phage Has a Deletion in the RII

Multiple Choice

One strain of rII- phage has a deletion in the rII region, another has a point mutation in the rII region.When E.coli K(λ) cells are infected with either rII- phage (not both) no plaques form.When E.coli K(λ) cells are infected with both rII- phage simultaneously plaques do form.Why do plaques form when E.coli K(λ) cells are infected with both types of rII- phage simultaneously?

A) Recombination between the two phage genomes resulted in a wild-type phage.
B) The two phage have mutations in different rII genes and their genomes complement each other.
C) A protein made by the deletion phage can repair the DNA of the phage with the point mutation.
D) Bacteria can survive infection with one phage, but they cannot survive infection with two phages.