The correct answer would be "to withstand the pressure of the blood that is being pumped by the heart".
Arteries are the type of blood vessels which carry blood away from the heart to rest of the body.
Thus, the blood which enters the arteries usually has high pressure due to the pumping of the heart.
To withstand and absorb this pressure, arteries usually have thick layers of muscular and elastic fibers in their structure as compared to the veins.
The wall of the arteries swells and expand due to the force generated with each contraction of the heart and then the arteries contract back which helps in pushing the blood forward.
Arteries have much thicker walls than other blood vessels in order to withstand the higher blood pressure that propels oxygenated blood away from the heart.
