In times of nutrient stress, the cellular slime mold Dictyostelium discoideum develops one of two cell types: pre-stalk and pre-spore. Scientists studying this development discovered that the pH of individual cells regulates the type of cell that is formed. Which of the following claims could scientists make about how environmental cues affect the gene expression of Dictyostelium discoideum?

What sentence best supports the statement that hormones are involved in the regulation of homeostasis? a. the hormone erythropoeitin increases the production of red blood cells when oxygen levels are low. b. the hormone oxytocin promotes labor contractions of the uterus during childbirth. c. the hormone melatonin induces sleep and its production is slowed by exposure to light. d. the hormone cortisol suppresses the immune system and is produced when the body is under stress.