The correct answer is Option 3. Key Points Calcium is useful for the formation of bones and teeth in the human body. The body needs calcium in order to circulate blood, move muscles, and release hormones. Bones are the body’s calcium reservoir. Ca2+ oscillations passed among platelets promotes blood clotting. ​ ​Additional Information When the body doesn’t get enough calcium from the diet, then it takes calcium from bones. The body doesn’t produce calcium, so it relies on the diet to get the calcium which body needs. Foods that are high in calcium include: Dairy products such as milk, cheese, and yogurt. Dark green vegetables such as kale, spinach, and broccoli. White beans. Calcium-fortified bread, cereals, soy products, and orange juices.​ Important Points Vitamin D is essential for the absorption of Calcium in the body. Sun Bath is a natural and best source of Vitamin D.