Hazardous wastes and water pollution for sure. Maybe even potential reactor accident
It could be stress or something
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 .
Second Hand Smoke is the correct answer
C) its the process of intraction with people, companies, etc.