There are several mechanisms through which reproductive isolation occurs. Which situation is an example of behavioral isolation? A.

Mules, the offspring of a male donkey and a female horse, are unable to reproduce because they are sterile.

B.

Males of different, closely related species of fireflies signal for mates by flashing different light sequences.

C.

The reproductive organs of snails only properly align when the male and female belong to the same species.

D.

Red and purple sea urchins cannot reproduce with one another because the sperm and egg cannot fuse.

B. Males of different, closely related species of fireflies signal for mates by flashing different light sequences.

Reproductive isolation refers to the inability of the members of a species to breed with members of other species. Behavioral isolation is a type of reproductive isolation, in which mating between the members of the species is facilitated by their behavior. It helps members of the same species to identity their mates. It prevents mating between population of distinct species.

Males of different, closely related species of fireflies signal for mates by flashing different light sequences is an example of behavioral isolation because flashing of light by fireflies is the behavioral characteristic which shows their desire for mating. The mates identify the light signals flashed by their partner belonging to the same species.

the sphincter muscles at the end of the digestive tract is the anus.

"1. it should be, it has been for about 20 years, and it's really not much different in the end than breeding animals to have particular traits. there are always concerns about genetically engineered animals/plants affecting the environment in unexpected negative ways, but i can't think of an example where the fears didn't turn out to be baseless.  

first, as you point out, it would be a great advance in pharmacology, to be able to tailor drugs and their doses to me. the pros involve better medical treatment. the cons involve privacy issues like insurance companies denying coverage to people with genetic risk factors. looking at dna markers wouldn't affect the frequency of genetic diseases, but it would allow detection of them earlier. and ok, actually i suppose that if people used this information to avoid having children with genetic diseases, some might decrease in frequency."