Which of the following strategies is most effective in preventing osteoporosis in older adults?

A. Regular weight-bearing exercise: Rationale: This stimulates bone remodeling and increases bone density, which is crucial in preventing osteoporosis. B. Taking calcium supplements: Rationale: Calcium is important, but by itself is less effective without physical activity or vitamin D for absorption. C. Avoiding all forms of physical activity: Rationale: Immobility accelerates bone loss and increases risk of osteoporosis and fractures. D. Limiting sun exposure: Rationale: Sun exposure is a natural source of vitamin D, which is essential for calcium absorption and bone health. Limiting it unnecessarily may be harmful.