Which equation is used to describe reaction rates?

S products−S reactants

∆H−T∆S

pV=nRT

∆(reactant or product)/∆time

chemical digestion occurs in the stomach were hcl and pepsin forms chyme, the mouth in which salivary amylase breaks down starch to form bolus, and the small intestine specifically the duodenum.

i think it's letter a.