The correct answer is Aorta.

- The aorta is the largest artery in the human body in terms of both diameter and caliber.
- It originates from the left ventricle of the heart and extends down to the abdomen, where it branches into the iliac arteries.
- The aorta is responsible for distributing oxygenated blood from the heart to all systemic arteries, supplying tissues throughout the body.

Key points to consider:
- The aorta has the largest diameter among arteries, typically measuring around 2.5-3 cm in adults.
- It functions as the main high-pressure conduit for oxygen-rich blood.
- Other arteries such as the common carotid artery, femoral artery, and pulmonary artery are large but have smaller calibers compared to the aorta.
- The pulmonary artery, although large, carries deoxygenated blood from the right ventricle to the lungs and is generally smaller in diameter than the aorta.

Understanding the size and role of the aorta is crucial in anatomy and cardiovascular physiology, as many clinical conditions such as aneurysms and dissections involve this major vessel.

Reference: Gray's Anatomy, 42nd Edition, Volume 1, Chapter 6 - The Aorta and Its Major Branches