Which can be used to characterize blood flow in the human body? A: There is a unidirectional blood flow. B: Arteries always carry oxygenated blood. C: Veins always carry deoxygenated blood. D: Arteries carry blood away from the heart. E: Veins carry blood toward the heart.
A) a, c, d, e B) a, b, c, d, e C) a, d, e D) b, c, d, e E) d, e