Correct Answer: A

Rationale: The correct answer is A: Low-density lipoprotein (LDL). LDL is often referred to as 'bad cholesterol' because it can lead to plaque buildup in arteries, increasing the risk of cardiovascular disease. High-density lipoprotein (HDL) is considered 'good cholesterol' as it helps remove LDL from the arteries, reducing the risk of cardiovascular issues. Very low-density lipoprotein (VLDL) and chylomicrons are also lipoproteins that transport fats in the bloodstream, but they are not as strongly associated with an increased risk of cardiovascular disease as LDL.

Correct Answer: C

Rationale: Vitamin B12 is primarily found in animal-derived foods like meats. Choices A, B, and D are incorrect as whole grains, nuts, and legumes do not naturally contain significant amounts of Vitamin B12. Therefore, the correct answer is 'C: Meats.'

Correct Answer: B

Rationale: The correct answer is B, 'dispensable.' Dispensable amino acids are those that the body can synthesize in sufficient amounts, so they are not required to be obtained from the diet. Indispensable amino acids, on the other hand, are essential and must be obtained from the diet because the body cannot produce them in sufficient quantities. Choices C and D, 'simple' and 'complex,' are incorrect as they do not accurately describe amino acids in terms of synthesis by the body.

Correct Answer: A

Rationale: The correct answer is A: 9. Nine amino acids are considered essential or indispensable because they cannot be synthesized by the body and must be obtained through the diet. These amino acids include histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine. Choices B, C, and D are incorrect as the number of essential amino acids is specifically 9, as they are crucial for various bodily functions.

Correct Answer: A

Rationale: The correct answer is A: act as buffers. Amino acids can act as buffers by helping to maintain the pH balance in the body. Choice B is incorrect because amino acids do not primarily facilitate glucose storage. Choice C is incorrect as amino acids do not regulate the heartbeat. Choice D is also incorrect because amino acids do not control the level of blood cholesterol.