The component of cigarette smoke responsible for addiction and for raising heart rate and blood pressure is

Explanation

Nicotine reaches the brain within seconds and acts on receptors there to give the reward that makes smoking so hard to give up, while also constricting arterioles and stimulating adrenaline release. Tar is the sticky carcinogenic residue that damages the airways, and carbon monoxide reduces the oxygen carrying power of the blood. All three are harmful, but only nicotine causes the dependence.