What factors are necessary for natural selection to occur? O Changes that occur as an organism grows can be inherited, such as increased muscle mass from exercise.
O A population's changes over many generations happen to help the organisms evolve to be more advanced
O Adaptations are specific to the current environment, and may no longer be beneficial if the environment changes.
O Adaptations are used to help organisms evolve and reach perfection and are independent of environmental factors.

A because

A population's changes over many generations happen to help the organisms evolve to be more advanced

O Adaptations are specific to the current environment, and may no longer be

answer: the blood-brain barrier is a layer of specialized membranes and cell processes designed to keep undesirable substances from passing from the bloodstream into the precious tissues of the brain. while the blood-brain barrier does keep most bad things out of the central nervous system, it is not impermeable.

explanation:

if, i suppose that a bee stings me swinging my hand away from a bee. then that if, i persist patient when a bee or wasp areas on your surface to investigate a scent or to take h2o and i secreting heavily, the bug ultimately will move of its personal agreement. if i don't need to set for it to disappear, lightly and gently wipe it off with a part of the paper.