Vitamin D isn’t like most other vitamins. Your body can make its own vitamin D when you expose your skin to sunlight. But your body can’t make other vitamins. You need to get other vitamins from the foods you eat. For example, you need to get vitamin C from fruits and vegetables. Also what makes vitamin D unique compared to other vitamins, is that when your body gets its vitamin D, it turns vitamin D into a hormone. This hormone is sometimes called “activated vitamin D” or “calcitriol.” Thus, option D is correct.