The correct answer is C.
An author's credentials can determine a health source's credibility. None of the other options would apply to credibility. When it comes to health, if you want to make sure that what you are researching or reading is authentic and reliable you need to find out whether the author is a professional health expert or not. You can do this by finding out their credentials.
Peer pressure
getting turned on . . .
The correct answer is C.
Age affects functional fitness. As one grows older, it becomes more difficult to maintains high level of fitness for various reasons. For instance, as one ages, the density and sizes of the bones in one's body shrink and they become more prone to fractures. Also, the energy level that one has reduces as one advances in age. Thus, as one grows older, it becomes necessary to participate less in physical activities.
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