During the Observations of a Species of Blue Moon Butterflies

Multiple Choice

During the observations of a species of blue moon butterflies on the Samoan island of Upolu, 99% of the butterflies were female and only 1% were male. Only five years later the male:female sex ratio was 1:1. What caused this?

A) Wolbachia lost the ability to kill all male butterflies.
B) Genetic changes in the Upolu butterflies resulted in suppression of the male-killing effect of Wolbachia.
C) Upolu butterflies evolved to become resistant to Wolbachia infection.
D) Upolu was recolonized by butterflies from the nearby island Savali, where sex ratios were closer to 1:1.