The Recent Discovery of Taste Receptors That Detect Sweetness in the Small

The recent discovery of taste receptors that detect sweetness in the small intestine illustrates that

A) chemical responses occur in only one part of the body.
B) new discoveries about anatomy and physiology are still being made.
C) everything there is to know about anatomy and physiology has been discovered.
D) the molecular and cellular level is of little interest in anatomy and physiology.