What is an allele? a. a group of proteins

b. a type of virus

c. a group of chromosomes

d. a form of a gene

D

Explanation:

According to the online dictionary: one of two or more alternative forms of a gene that arise by mutation and are found at the same place on a chromosome.

humans can cause extinction of a species through overharvesting, pollution, habitat destruction, introduction of invasive species (such as new predators and food competitors), overhunting, and other influences. explosive, unsustainable human population growth is an essential cause of the extinction crisis.

explanation:

i didn't have the answer choices , but i tried my best.