Final answer:
Estrogen receptor blockers are used in the treatment of breast cancer and selectively block estrogen in breast tissue but not in other beneficial areas such as the uterus, bones, and cardiovascular system.
Step-by-step explanation:
Estrogen receptor blockers selectively block the action of estrogen in breast tissue, a strategy commonly used in the treatment of breast cancer. These blockers, however, allow estrogen to act in other areas of the body where its role can be beneficial or neutral. Estrogen plays a critical role in the development and regulation of the female reproductive system, in bone density maintenance, and in the regulation of cholesterol levels in the blood.
While these blockers limit estrogen's influence on breast tissue, they do not inhibit its activity in organs such as the uterus, the skeletal system, or the cardiovascular system. Patients with a high expression of the estrogen receptor in their breast tumors (answer c from the provided sequence) are the ones who stand to benefit the most from treatments that target estrogen receptors, such as selective estrogen receptor modulators (SERMs) or aromatase inhibitors, which reduce the production of estrogen.