Question

cathy went through gastric bypass surgery. the surgery reduced the size of her stomach. this reduced her appetite because her remaining stomach produced less: orexin. ghrelin. pyy. leptin.

Explanation:

Ghrelin is an appetite - stimulating hormone mainly produced by the stomach. Reducing stomach size would decrease ghrelin production. Orexin is produced in the hypothalamus. PYY (peptide YY) is produced in the intestines and suppresses appetite. Leptin is produced by fat cells.

Answer:

ghrelin.