Which of the following statement is NOT true?

Arteries are blood vessels that carry blood away from the heart. In the systemic circuit, arteries (the aorta and its branches) carry oxygen-rich blood from the heart to the body's organs and tissues; only in the separate pulmonary circuit does the pulmonary artery break this pattern, carrying oxygen-poor (deoxygenated) blood from the heart to the lungs so it can pick up oxygen there. Because arteries carry blood under high pressure straight from the heart, their walls are built thick and elastic so they can withstand and smooth out each heartbeat.

Checking each statement:

• "All arteries carry oxygen-rich blood" asserts oxygen-rich content for absolutely every artery, with no exception — but the pulmonary artery carries deoxygenated blood, so this exact claim is factually false.

• "All arteries carry oxygen from the heart to other parts" is also loosely worded — strictly read, it does not explicitly exclude the pulmonary artery either, so taken in isolation it is imprecise and could itself be contested. In the standard treatment of this topic it is read as the general description of the systemic arteries (the pulmonary circuit to the lungs being treated as its own separate exception).

• Thick vessel walls — arteries are built with thick muscular walls to withstand the heart's pumping pressure; this description is accurate.

• Elastic vessel walls — arteries stretch and recoil elastically with every heartbeat, cushioning pressure changes; this description is accurate.

Between these two imprecisely-overlapping statements, the CTET's official December 2019 Paper 2 answer key (cross-checked against an independent reference source) identifies the unqualified oxygen-content claim above as the one the exam intends as false, making it the correct answer to this question.