The passage of nutrients and other substances into the walls of the gastrointestinal tract and then into the bloodstream is called
a. digestion.
b. absorption.
c. metabolism.
d. molecular function.

Gastrointestinal Tract (GI) , or also known digestive tract, is the connected series of organs and structures used for digestion of food and absorption of nutrients.

The passage of nutrients and other substances into the walls of the gastrointestinal tract and then into the bloodstream is called absorption. Correct B

Once foods are broken into small enough parts, your body can absorb and move the nutrients to where they are needed.