Answer: Possession of Valves
Explanation: Veins possess valves which ensures that blood flows in only one direction. Valves helps blood to flow back to the heart against gravitational force.
Arteries don't have valves because the pressure originating from the heart is capable of causing the blood to flow in one direction.
the correct answer is the first one. density = mass / volume.
i hope this helped!
Answer: B and C
Explanation: Both are below 6 on the scale so their not as hard or tough.
move in a circle on a central axis.
