If a correlation is -1.00, then which type of relationship exists?

Why is it so difficult for many toxins and poisons to penetrate the blood-brain barrier?

a. Because the human immune system has killer t-cells that attack such foreign agents. b. Because those agents are too large to get out of the human blood stream. c. Because the presence of such invaders triggers a fever, which kills them. d. Because those agents are not soluble in fat.

What does the Greek word "glia" mean?

a. Neuron b. Glue c. Connection d. Fat