What conclusion can you make about the skeletal structure of these two organisms? A. They share a common ancestor, but they’re different species. B. They’re the same species. C. They’re different species with no evolutionary relationship. D. The four-legged organism directly evolved from the two-legged organism.

It's is A. They share a common ancestor, but they're a different species.

b

explanation:

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: