Which of the Following Is an Example of Evolution as a Result

Which of the following is an example of evolution as a result of selection acting on genetic variation?

A) Achromatopsia (extreme sensitivity to light and lack of color vision) becomes widespread among individuals on an isolated island because a common ancestor carried a mutant gene.
B) A random mutation produces a novel odorant receptor that allows a fly to detect a specific fruit, allowing it to monopolize a new food source and produce more offspring.
C) In a small population of birds, more individuals that produce one song variant reproduce than those that produce a different song variant, just by chance.
D) Frog eggs that happen to be laid during a severe drought are much less likely to survive than their siblings that developed in a wetter month.
E) All of the above