The answer to the first one is C. Stress
Stress can lower the immune system if experience constantly. This is because the body is focused on reducing the cause of the stress rather then fighting off potential illnesses. Also being stressed takes a lot of energy that is eventually taken away from other functions in the body, such as the immune system
The second answer is B. Rub your hands vigorously with warm, soapy water, for 15 seconds
^^^This ensures that most of the bacteria on your hands is most effectively killed
Hope this helped!
~Just a girl in love with Shawn Mendes