Cigarette manufacturers purposefully add to cigarettes in order to give them a particular flavor.

The given blank can be filled with additives.

Explanation:

The manufacturers of cigarettes may also supplement various additives to a cigarette to cover the harsh flavor and the feeling of smoke and thus make smoking more tempting. The flavor additives like sugar and menthol may be added to cigarettes to modify the taste of smoke and thus makes it easier to draw in.  

These and other additives, like some chemicals, such as ammonia is added to cigarettes in an attempt to augment the delivery of nicotine and absorption by the lungs. Even some of the additives act as bronchodilators, which can open the lungs and enhance the concentration of dangerous chemicals, which are engrossed.  

answer(b) keep oxygenated and deoxygenated blood separate;