Fungiform papillae are most numerous in:

Correct Answer: B

Rationale: Fungiform papillae are scattered across the oral part of the tongue but are most concentrated at the edges and tip, where taste perception is heightened.

Correct Answer: B

Rationale: The gastric surface epithelium secretes neutral to alkaline mucus with bicarbonate to protect the mucosa from acid and pepsin.

Correct Answer: B

Rationale: Carcinoid tumors arise from enteroendocrine (APUD) cells, which secrete hormones like serotonin.

Correct Answer: D

Rationale: Hepatocytes have microvilli facing the space of Disse, but not a brush border, which is characteristic of intestinal enterocytes.

Correct Answer: A

Rationale: Sieve plates are clusters of fenestrae in the endothelium of hepatic sinusoids, allowing plasma exchange with the space of Disse.