Chemotherapy is a cancer treatment that uses drugs to kill cancer cells. However, it is problematic, because the drugs also kill every healthy cell that they contact. How could nanotechnology best be used to improve the treatment of cancer with chemotherapy?

A: A nanometer-size carrier could be designed to bring the chemotherapy drugs only to cancer cells.
B: A nano carbon wire could be designed that would aid in the manufacture of chemotherapy drugs.
C: A quantum dot could be used to watch where the chemotherapy drugs go in the body.
D: Biomaterials could be made that would allow for cell growth within the cancer cells so that they are easier to find.