Which of the following is true about veins? 1. Veins have valves; arteries do not. 2. Veins carry blood away from the heart, while arteries carry blood to the heart.3. Veins are more muscular than arteries.4. Veins have a smaller diameter lumen than arteries.

What is the main difference between the central nervous system (cns) and the peripheral nervous system (pns)? .the cns involves the brain and spinal cord, and the pns involves the body nerves. the cns involves the body nerves, and the pns involves the brain and spinal cord. the cns involves sensory neurons, and the pns involves motor neurons. the cns involves motor neurons, and the pns involves sensory neurons.