There is unidirectional flow of blood in the arteries due topresence of valveshigh pressure of blood from the heartinelastic walls of arteriesnone of the above

The unidirectional flow of blood in the arteries is due to the high pressure of blood from the heart. Here's a step-by-step explanation:

1. The heart pumps blood out into the arteries through a process called systole. This is when the heart's ventricles contract to push blood out of the heart.

2. This action creates a high pressure, which propels the blood forward into the arteries.

3. The arteries, being elastic, expand to accommodate the surge of blood.

4. When the heart relaxes (a phase called diastole), the arteries contract. This helps to maintain the pressure and keep the blood moving in one direction.

5. It's important to note that arteries do not have valves like veins do. The high pressure from the heart is sufficient to ensure unidirectional blood flow.

So, the correct answer to your question is "high pressure of blood from the heart".