Fact 1: Caffeine is a central nervous system stimulant.

Fact 2: Like caffeine, nicotine is a stimulant.

Given the two facts above, answer the question "What stimulates the central nervous system?" with the following options: 
- nicotine
 - exercise
 - a chime
 - Energy
 - A computer
 - sweating
 - a doorbell
 - acetic acid


 

 nicotine        