An investigator who conducts an experiment to determine how changes in pH affect the function of enzymes on digestion is most likely to be a/an ________.

A) neurologist
B) anatomist
C) engineer
D) physiologist
E) histologist

Physiologists study the functions of living organisms and their parts, including how systems like the digestive system work and how external factors like pH levels can affect these functions. This makes a physiologist the most likely investigator in an experiment focused on the effects of pH changes on enzyme function in digestion.