What does the prefix cardio refer to

According to positive psychologists, an individual’s subjective well-being consists of one’s and a. overall level of happiness . . life satisfaction b. goal accomplishments . . money earned c. idea of self-importance . . social acceptance d. level of self-esteem . . pride sorry am i just not getting it or is this worded confusingly xd

In which way does nicotine cause addiction? by stimulating the brain's pleasure center by increasing blood-sugar levels by decreasing dopamine levels by reducing depression and anxiety

Which of the following is not a symptom of chronic fatigue syndrome a) pain in joints with swelling b) low-grade fever c) unexplainable muscle weakness or pain d) forgetfulness, irritability, and confusion