In school, you are taught that smoking is bad for your health. So? We can associate the word "danger" in the sentence with the world "smoking".
Service: Not related to health(smoking), so we can get rid of options A and B. Health: Related to health(smoking), so keep B and D.
Message: A communication containing some sort of information. Keep B. Initiative: As defined by dictionary.com, "an introductory act or step; leading <span>action" </span> Warning the public against something does not fit, so discard D. <span> We are left with Option B.
