When the skin is exposed to ultraviolet rays, the skin produces a molecule that is turned into Vitamin D.
Sun is the source of ultraviolet rays important for Vitamin D production. Due to this reason, in the case of Vitamin D deficiency, it is recommended by doctor's to absorb sunlight by skin. The Vitamin D production occurs specifically by UV B rays rays which lie in the range of 290-315 nanometer.
The chemical 7-dehydrocholesterol absorbs these rays and convert to previtamin D3. Further, previtamin D3 isomerizes to Vitamin D. Other than sunlight, Vitamin D can be taken through diet. The sources include seafood like fish, fish oil, dairy products, beef liver etc. Vitamin D is required for bone and teeth formation, muscle contraction, immune system etc.
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The answer is C. Targeting a particular area for improvement
Specificity principle stated that whatever you do in the gym, should be relevant to your desired outcome
For example, if you are a rowing athlete, it should be best if you focus on upper body training more than lower body because you need your upper body strength more than you need the lower
Running cardio biking pull ups ?
The answer is a frequency, intensity, time, and type
According to the dietary guidelines for Americans which of the following is important in order to maintain a healthy weight.
D. Eat nutrient-dense food
