Well i think the answer is pretty one sided , How bought that rehab
Specificity is a Training principle that states whatever you do in your training, should be relevant for your desired outcome it's important because your whole fitness program should be adjusted based on that specificity.
C.<span>Janine should increase the intensity or length of her exercise programs because it is more difficult to maintain high fitness levels as you age.</span>
The answer to your question, is C getting sick more often
hope this helps :D
I need the full question to answer as well as the graph and/or any examples you have.