When lactose is not present, what happens to E. coli is that the genes that produce the enzymes needed to break down lactose are not expressed. The correct answer is B.
prophase
Further genetic variation comes from crossing over, which may occur during prophase I of meiosis. In prophase I of meiosis, the replicated homologous pair of chromosomes comes together in the process called synapsis, and sections of the chromosomes are exchanged.
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