Which of the Following Statements About Research on Smoking Cessation

Which of the following statements about research on smoking cessation is true?

A) Quitting for good typically requires just one try, as the stages of change model suggests.
B) Lighter smokers have more success with "going cold turkey" than heavier smokers.
C) Bupropion SR (sold as Zyban) is an antidepressant that is commonly prescribed to smokers who are trying to quite, but unfortunately research does not confirm that this drug is effective.
D) Research confirms that giving up smoking is not difficult, especially in the early days of quitting.