سوال ۱۵ کنکور ارشد مهندسی برق ۱۴۰۰

Cloze test. Read the passage and choose the option that best fits blank (15).

For some time now, medical scientists have noted an alarming increase in diseases of the heart and circulation among people who smoke cigarettes. (11) .......... in the bloodstream causes blood vessels to contract, thus (12) .......... circulation, which eventually leads to hardening of the arteries. (13) .......... the arteries stiffen, less blood reaches the brain, and the end result of this slowdown is a cerebral hemorrhage, commonly (14) .......... to as a “stroke”. In addition, (15) «..........» reduces the ability of the hemoglobin to release oxygen, resulting in shortness of breath.