Gastrin, histamine, endorphins, serotonin, cholecystokinin, and somatostatin are hormones or paracrines that are released directly into the lamina propria. Which of the following cell types synthesize and secrete these products? a) parietal cells
b) enteroendocrine cells
c) mucous neck cells
d) zymogenic cells

The correct answer is option b, that is, enteroendocrine cells.

Explanation:

The specialized cells of the pancreas and the gastrointestinal tract exhibiting endocrine function are termed as enteroendocrine cells. These cells generate gastrointestinal peptides or hormones in response to a distinct kind of stimuli and discharge them into the bloodstream for the systemic effect. These are the most varied endocrine cells found within the body.  

The intestinal enteroendocrine cells produce somatostatin, cholecystokinin, motilin, enteroglucagon, and neurotensin hormones. The G cells present within the intestine produce gastrin. In the gastric glands, the gastric enteroendocrine cells are present, which produce histamine, and others like cholecystokinin, alpha and gamma-endorphin, somatostatin, and others.  

In the islets of Langerhans, the pancreatic enteroendocrine cells are present, which produce hormones like ghrelin, amylin, somatostatin, and pancreatic polypeptide.  

if your own plato the answer is b. the fern transitioned from sporophyte generation to gametophyte generation.