c) is the best answer here
Bacteria have tiny genomes in comparison with elephants: they also have much simpler mechanisms of transcription, translation and replication. They use different polymerases with lower fidelities than those in elephants. Further, because they live such short lives and reproduce so fast, it is likely that at least one bacterium in a culture will hit on the mutation that helps survival in the changed environment. Lateral gene transfer then ensures that the rest of the bacteria also receive this mutated gene - and the population continues to live.
