Answer: B) The uptake of nutrients and substances from the digestive tract into the bloodstream.
Explanation: Absorption refers to the process by which cells within the body intake nutrients that are flowing through the blood stream. The circulatory system is responsible for delivering nutrients from the digestive system to the rest of the body so that these nutrients can be absorbed for bodily functions.
The process of breaking down food in the digestive system is a process known as digestion, so choice a is incorrect.
Answer choice C refers to a process known as excretion, so it is incorrect. When referring to the removal of waste from the body, biologists usually use the term excretion.
Answer choice D is incorrect because the release of hormones into the bloodstream is usually known as secretion.