Correct Answer: D

Rationale: Villi and microvilli in the GI tract serve to increase the surface area of the small intestine, aiding in the absorption of nutrients into the bloodstream. Choices A, B, and C are incorrect as villi and microvilli are primarily involved in enhancing absorption, not in producing bile, killing bacteria, or producing vitamin K.

Correct Answer: C

Rationale: The correct answer is C: vomiting. Infants breastfed by mothers who smoke are more likely to experience vomiting and gastrointestinal issues due to the transfer of nicotine and other harmful substances through breast milk. Choices A, B, and D are incorrect. Poor temperature regulation, vision impairment, and elevated blood pressure are not the primary outcomes closely associated with breastfeeding infants of mothers who smoke.

Correct Answer: B

Rationale: Alcohol does contain energy and provides calories, but it is not considered a nutrient. Nutrients are substances that contribute to essential bodily functions. While alcohol may have energy, it does not provide essential vitamins, minerals, or other nutrients necessary for the body's health. Additionally, excessive alcohol consumption can have harmful effects on the body, further supporting why alcohol is not classified as a nutrient.

Correct Answer: A

Rationale: Excessive supplementation of calcium and vitamin D beyond the upper intake level is not recommended unless under medical supervision, as it can cause adverse health effects.

Correct Answer: B

Rationale: The correct answer is B, milk. Milk is known for being one of the best dietary sources of calcium, essential for bone health and various bodily functions. Soy products, cereal grains, and dark green vegetables are good sources of calcium as well, but milk generally has a higher calcium content compared to these options.