Which of the following refers to fibrocystic breast disease?
a. progressive development of fluid-filled cysts and fibrous tissue
b. the proliferation of atypical cells with high risk of malignancy
c. benign tumors that develop after menopause
d. any tissue changes other than the normal response to hormonal changes

The correct option is a. Fibrocystic breast disease refers to the progressive development of fluid-filled cysts and fibrous tissue.

Explanation:

Fibrocystic breast disease is characterized by benign (non-cancerous) changes in fibrous tissue. These changes may include irregular lumps or cysts (Breast cysts are sacs full of fluid inside the breast) which tend to mix with the surrounding fibrous tissue, breast swelling, nipple tenderness. Fibrocystic breasts are composed of tissue that can have a lumpy or rope-like texture. Which is called "nodular or glandular breast tissue" in it, there are observable characteristics of the disease through the microscope as: a prominence of fibrous tissue, excessive growth of the cells lining the breast ducts, enlargement of the mammary lobes and the fluid-filled cysts.