【单选题】Cancer is among the top killer diseases in our society today and scientists have found out that stress helps to bring it on. It is worthwhile to consider, therefore, what are the causes of stress in o...
A.
Freedom from responsibilities helps relieve stress.
B.
Stress is the direct cause of cancer.
C.
The causes of stress are worthy of serious study.
D.
Cancer is the number one killer in our society today.