Pulmonary artery: deoxygenated blood, low pressure (15-20 mmHg)

Steps:

• Identify key traits: pulmonary artery carries deoxygenated blood from heart to lungs at low pressure (systolic 15-30 mmHg, mean ~15 mmHg).
• Examine options for deoxygenated status and pressure range matching 15-20 mmHg.
• Rule out oxygenated options, as pulmonary artery blood lacks oxygen.
• Confirm A aligns with deoxygenated blood and appropriate pulmonary pressure.

Why A is correct:

• Pulmonary artery definition: transports deoxygenated blood to lungs at low pressure (15-20 mmHg range), directly matching A's description.

Why the others are wrong:

• B: Oxygenated blood with high pressure (80-120 mmHg) identifies systemic aorta.
• C: Oxygenated blood at very low pressure (3-5 mmHg) describes pulmonary veins.
• D: Deoxygenated blood at low pressure (3-5 mmHg) matches systemic veins like vena cava.

Final answer: A