Scientists believe there is a link between cigarette smoking and cancer. evidence for this inference includes which statement?
a) rates of lung disease are significantly increased among smokers.
b) one brand of cigarettes sold more than 44 million packs last year.
c) chemicals found in tobacco may be both physically and physiologically addictive.
d) according to a recent study, 7 out of 10 smokers who try to quit smoking begin smoking again within one month.