What can cause apnea?

Apnea is defined as a temporary cessation of breathing, which can occur for various reasons. The correct answer identifies that apnea is directly related to factors leading to cessation of breathing. This can include a variety of issues such as obstructive conditions (like sleep apnea where the airway is blocked), central nervous system problems that affect the brain's ability to signal breathing, or severe respiratory conditions.

High blood pressure and weight gain are associated with a range of health issues, including respiratory complications, but they do not directly cause apnea in the same way that specific factors leading to the cessation of breathing do. Low sugar levels can have numerous effects on the body's functioning, including confusion and potential loss of consciousness, yet they are not a primary cause of apnea. Thus, the understanding that apnea is caused by specific factors that result in the interruption of normal breathing makes the selection of this answer particularly appropriate.