Hello there!
The answer to your question is D. chromium.
Hope this helps you!
-Dark or heavy clothing
-Not staying hydrated
A RN Nurse would be better and quicker and a good start. Many schools are forwarding that position and beginning to make classes about it, as the nurse job is the future.
That's my opinion, take it from a Fire Fighter and soon to be EMT.
B . It is completely normal . However if you are experiencing extreme pain stop and consult your doctor . Also if you are prone to any kind heart disease let someone know where you are when exercising or better yet let them be at your side at all times .