Why Is It a Good Idea for a Bacterial Cell

Multiple Choice

Why is it a good idea for a bacterial cell to be able to use glucose FIRST as an energy source (until it is depleted) , THEN switch to lactose?

A) Lactose can only be used by a small number of bacteria as an energy source AND for conservation of energy: why use the energy to make the enzymes for breaking down lactose when glucose doesn't need any extra enzymes for breakdown?
B) For conservation of energy: why use the energy to make the enzymes for breaking down lactose when glucose doesn't need any extra enzymes for breakdown AND because breakdown of lactose produces inhibitory compounds.
C) Glucose is an easier compound to break down and obtain energy from than lactose AND for conservation of energy: why use the energy to make the enzymes for breaking down lactose when glucose doesn't need any extra enzymes for breakdown?
D) Glucose provides 10x as much energy when broken down as lactose AND for conservation of energy: why use the energy to make the enzymes for breaking down lactose when glucose doesn't need any extra enzymes for breakdown?
E) For conservation of energy: why use the energy to make the enzymes for breaking down lactose when glucose doesn't need any extra enzymes for breakdown AND because lactose always triggers endospore formation, which may be unnecessary.