Investigation of robins a Student notice for you to robins in her yard during the winter if she thinks that some robins most migrate in the winter she counts the robins in her yard once a week for two years she finds that there are about half as many robins in her yard in the winter as in the summer her research has shown that some robins are not in her Hypothesis

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 answer to your question is:

c. complementary base-pairing