15. Sarah is a biologist who is studying a species of crab. In the wild, crabs with larger
pincers will have greater reproductive success than those with smaller pincers. To
investigate this further, she placed 50 crabs with small pincers and 50 crabs with large
pincers together in an isolated area that closely resembled their natural environment.
She observed several generations of the crabs over the next ten years. If her
experimental setup replicates the natural selection process in the wild, which result is
most likely to be observed?
A.the crabs born with small claws would develop larger claws and pass this trait to their offspring
B.The percentage of crab as with large claws would increase.
C.The percentage of crabs with small claws would increase.
D.the DNA in crabs with small claws would mutate in order to produce larger claws.

Crabs with large claws have more chances to survive and reproduce; this biological advantage will make most of these crabs to successfully reproduce through generations and pass this feature to their offspring. On the opposite, crabs with smaller pincers do not have this reproductive or survival advantage, this implies many crabs with small pincers will not survive a long time or will not reproduce, and therefore this trait will not past to their offspring. Moreover, this situation will cause after many generations the large claws trait prevails, while the small claws trait decreases because crabs with larger claws are more suitable. According to this, it is expected the percentage of crabs with large claws would increase.