You Mix Met⁺ Pro- and Met⁻ Pro⁺ Auxotrophic Strains of E.coli.If

You mix Met⁺ Pro- and Met⁻ Pro⁺ auxotrophic strains of E.coli.If you incubate for one hour before plating to detect prototrophs,no colonies are seen,but if the incubation time is increased to three hours,prototrophic colonies form.What possible explanations could there be for this observation? (Select all that are plausible)

A) gene transfer cannot take place in such a short time
B) E) coli cannot replicate in one hour
C) Cells cannot take up DNA in one hour
D) Mutation cannot take place within one hour
E) All answers are equally likely