Mary wants to train for a half marathon. she needs to increase her which of the following activities will mary the most?

How do the uv rays cause damage?   what exactly causes the skin to burn;   can you be more specific about this mechanism?   3. how do photosensitive medications increase a person's sensitivity to sunlight and therefore increase their risk of getting burned?     what kind of medications can increase photo-sensitivity, can you think of some examples?

What type of medicine to people take if they are lactose intolerance

Which of these contraceptive methods would be most beneficial for a female who wishes to avoid side effects or surgery?