Definition: Arid region that receives less than 10 inches of precipitation annually. Example: Sahara, Mojave, Antarctica

Alaska and northern canada have a diet rich in vitamin d and their skin color is darker than predicted on the basis of iv intensity at their latitude. explain the observation:

Look at the following answer choices and determine which belongs in the both category. testable, can be disproven explains natural phenomena, has evidence to support it prediction, tentative, one or more scientists working together well established, many different scientists working independently, highly reliable

The body is protected against harmful flu viruses by