<prompt> In a coho study nonsmokers were found to have carcinoma lung. This indicates -Smoking does not cause lung cancerEtiology for lung Ca is multifactorialSmoking is the only cause of lung cancerPassive smoking also increases lung cancer  <response>: Ans. is b i.e., Etiology for lung Ca is multifactorialo Smoking is not specific for lung cancer becausei Not everyone who developed lung cancer has smoked -- Other etiological factors other than smoking are also involved in causation of lung cancer, i.e., etiology of lung Ca is multifactorial.Not everyone who smoke develops lung cancer. 