Which of the following is a potential adverse effect of combined oral contraceptives [COC]?

A. Increased risk for osteoporosis: Combined oral contraceptives contain estrogen and progestin, and estrogen has a protective effect on bone mineral density. Estrogen supports osteoblastic activity and helps maintain bone remodeling balance, contributing to preservation of bone mass. COCs are not associated with increased osteoporosis risk and may provide some protection. B. Increased risk of ovarian and uterine cancers: Use of combined oral contraceptives is associated with a reduced risk of ovarian and endometrial cancers. Suppression of ovulation decreases repeated ovarian epithelial trauma, which lowers the risk of malignant transformation. Progestin components also counteract estrogen-mediated endometrial proliferation, lowering the risk of endometrial hyperplasia. C. Increased bleeding and iron deficiency anemia: Combined oral contraceptives generally reduce menstrual blood loss by stabilizing the endometrial lining and suppressing excessive endometrial proliferation. Shorter and lighter menstrual periods occur in many users, which contributes to improved iron stores and may reduce the likelihood of iron deficiency anemia. D. Increased risk of venous thromboembolism: Estrogen-containing contraceptives increase hepatic synthesis of clotting factors such as fibrinogen and factors VII, VIII, IX, and X, promoting a procoagulant state. Reduced levels of anticoagulant proteins such as protein S also contribute to increased coagulation potential. These hemostatic changes elevate the risk of venous thromboembolism, including deep vein thrombosis and pulmonary embolism.