Some Butterflies Can Ingest Toxic Chemicals from the Milkweed Plants

Multiple Choice

Some butterflies can ingest toxic chemicals from the milkweed plants they feed on and then can store those chemicals in their body. Because toxins stored in the butterflies are toxic to birds, the birds avoid eating the butterflies. Which of the following is the best explanation for this situation?

A) Butterflies that stored the chemicals were never eaten by predators, so those butterflies survived.
B) Butterflies developed a mutation that led them to be able to store the chemical because they needed to avoid being eaten.
C) Milkweed plants wanted the butterflies to ingest the chemical so they would no longer feed on the plant, but the butterflies fooled the milkweed by storing the toxic chemicals.
D) Any butterfly allele that allowed milkweed toxin storage would be likely to persist because butterflies that had it were more likely to survive.