An insecticide kills most of the ants on a plant. Over time, it is determined that the insecticide is not as effective for killing ants. Which statement best explains this observation?

A The ants killed initially by the insecticide were genetically the same as the surviving ants.

B The ants killed initially by the insecticide had thinner cell membranes than the surviving ants.

C The ants that survived were younger than those that died as a result of the insecticide.

D The ants killed by the insecticide and the surviving ants were genetically different. ​