Correct Answer: C

Rationale: The correct answer is C: Carcinomas. Carcinomas are cancers that originate from epithelial tissues, which are the tissues lining the surfaces of organs and structures in the body. Leukemias (choice A) are cancers of the blood-forming cells, not epithelial tissues. Myelomas (choice B) are cancers that develop in plasma cells in the bone marrow, not epithelial tissues. Sarcomas (choice D) are cancers that arise from connective tissues like bone, cartilage, or muscle, not epithelial tissues. Therefore, choices A, B, and D are incorrect in the context of cancers originating from epithelial tissues.

Correct Answer: B

Rationale: Cariogenic foods and beverages lower the pH level in the mouth to below 5.5. This is a critical threshold, as it is the point at which enamel begins to demineralize, increasing the risk of dental caries. Therefore, options 'A', 'C', and 'D' are incorrect. Although a pH level of 5, as suggested by option 'A', would indeed lead to demineralization, it's not the threshold value. The pH levels suggested by options 'C' and 'D' (6 and 6.5, respectively) are higher than the critical value of 5.5, which means they would not initiate enamel demineralization and the subsequent risk of dental caries.

Correct Answer: D

Rationale: Nucleic acids, such as DNA and RNA, are the biomolecules responsible for storing and transferring genetic information within cells. Carbohydrates, proteins, and lipids do not have this specific function. Carbohydrates are mainly used for energy storage, structural support, and cellular communication. Proteins are involved in various cellular functions such as enzymatic reactions, structural support, and signaling. Lipids play roles in energy storage, cell membrane structure, and signaling.

Correct Answer: B

Rationale: Alcohol abuse is indeed a major cause of acute pancreatitis, along with gallstones, accounting for the majority of cases. While infections, diabetes, and obesity can also contribute to pancreatitis, they are not as prevalent as alcohol abuse and gallstones in causing acute pancreatitis.

Correct Answer: D

Rationale: The first statement is false; fluoride is not added to infant formulas due to the risk of fluorosis. The second statement is true; breast milk contains low levels of fluoride.