Certain Receptor Tyrosine Kinases (RTKs) That Promote Excessive Cell Division

Certain receptor tyrosine kinases (RTKs) that promote excessive cell division are found at high levels in various cancer cells. HER2 is an RTK that is present at excessively high levels in some breast cancer cells. Herceptin is a protein that binds to HER2 and inhibits cell division. Herceptin may be an effective treatment for breast cancer treatment under which of the following conditions?

A) If injection of HER2 in the patient's cancer cells inhibits cell division.
B) If the patient's cancer cells have excessive levels of HER2.
C) If the patient lacks functional HER2 proteins.
D) If the patient has excessive levels of other RTKs in cancer cells.