Which of the following provides the best example of a change in genetic
traits over several generations in response to natural selection?

a) Farmers choose to plant only seeds from those crops that proved to be resistant to
insects.

b) The number of spots on a group of giraffes varies from one individual to the next

c) A group of chimpanzees learns to communicate with their trainer to obtain food.

d) The average root depth of one species of plant increases as annual rainfall in the area goes down.

d) The average root depth of one species of plant increases as annual rainfall in the area goes down.

Explanation:

they deliver oxygen to the blood

answer: decrease

a limiting factor is the one which decrease the abundance, distribution and causes extinction of the population of species in a ecosystem. here, predators including hawks, owls and snakes are the limiting factor for the population of mexican free tailed bat.   although bats are nocturnal animals as they forge for food at night these predators also may remain active during night which can decrease the population of the mexican free-tailed bats. also, these bats eat only one type of insects that are moths. the food can also be a limiting factor as all 400 members are dependent upon same type of food needs that are moths. the decrease in the moth population can cause decrease in population size of the mexican free-tailed bats.

therefore, the scenarios will most likely to decrease the population size of the mexican free-tailed bats.