Apopulation of rabbits lives in a forest. the habitat features many small spaces for hiding. over many generations, the average size of the rabbits gets smaller and smaller. what type of selection is this?

Directional Selection.

Explanation:

This process can be defined as the positive selection in which one phenotype is selected over the other phenotype, causing the allele frequency to shift towards the other phenotype.

The allele favored by directional selection is advantageous. There is a increase in the rate of reproduction and chances of survival.

Here, the population of rabbits are decreasing in size over a period of time because they adapted the burrows to live in. Gradually small size of the rabbits were favored.

This is an example of directional selection.

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:

the endomembrane system i think