Correct Answer: C

Rationale: The question has been corrected to specify the structure responsible for reabsorbing water, salts, and nutrients in the kidneys. The correct answer is the nephron, which is the functional unit of the kidney that performs filtration and reabsorption processes. The renal artery brings blood into the kidney for filtration, the renal vein carries filtered blood away from the kidney, and the glomerulus is a part of the nephron where filtration occurs. Therefore, the nephron is the structure that reabsorbs substances and returns them to the body.

Correct Answer: A

Rationale: The primary function of the coronary arteries is to carry oxygenated blood to the heart muscle. Oxygenated blood is crucial for providing nutrients and oxygen to the heart muscle cells, enabling the heart to work efficiently. Without this oxygenated blood supply, the heart muscle may not receive the required nutrients and oxygen, potentially resulting in heart damage or dysfunction. Choices B, C, and D are incorrect as coronary arteries do not carry deoxygenated blood from the heart muscle, pump blood to the lungs for oxygenation, or regulate blood pressure in the systemic circulation. The coronary arteries specifically supply oxygenated blood to the heart muscle to support its function and vitality.

Correct Answer: A

Rationale: The correct answer is A: Pulmonary vein. The pulmonary vein carries oxygenated blood from the lungs to the heart. It is essential to distinguish between the pulmonary vein (A) and the pulmonary artery (B) in this context. The pulmonary vein transports oxygenated blood, while the pulmonary artery carries deoxygenated blood from the heart to the lungs for oxygenation. The aorta (C) functions as the main artery that delivers oxygenated blood from the heart to the body's tissues, while the vena cava (D) returns deoxygenated blood from the body to the heart.

Correct Answer: B

Rationale: The correct answer is B: Ball-and-socket joint. The ball-and-socket joint, like the shoulder joint, allows for the greatest range of motion due to its structure, enabling movement in multiple directions. In contrast, hinge joints, pivot joints, and saddle joints have more restricted ranges of motion compared to ball-and-socket joints. Hinge joints primarily allow movement in one plane, pivot joints allow rotation around a central axis, and saddle joints have limited movement compared to ball-and-socket joints.

Correct Answer: B

Rationale: An atom is the fundamental building block of matter, while molecules are formed by the combination of atoms.