How does the section “A Complex Fluid” contribute to the development of ideas in the text? A It reveals why some doctors refuse to give blood transfusions to patients in need.

B It compares how human blood and artificial blood function in the body after a transfusion.

C It suggests that the properties of human blood make it impossible for scientists to develop an artificial substitute.

D It describes the various functions of blood in the body and the challenges associated with using it for a transfusion.

Which two details support the answer to Part A?

A “Blood moves through a person’s veins, delivering nutrients to all the cells that make up the body.” (paragraph 5)

B “Red blood cells contain hemoglobin.” (paragraph 6)

C “ ... that’s why a person who loses a lot of blood might not survive without a transfusion.” (paragraph 6)

D “Patients must receive a compatible blood type from a donor ... ” (paragraph 7)

E “ ... where donated blood is screened for common pathogens that can make people sick.” (paragraph 8)

F “Artificial blood could solve these problems.” (paragraph 9)