<prompt> All are chemical carcinogens exceptBeta caroteneBenzeneThorostatNitrates  <response>: Ans. a Betacarotene. Ref. Robbin Pathology, 6th ed., 307CHEMICAL CARCINOGENSDirect actingProcarcinogensOthersa-propiolactoneBenzopyreneThorostatDimethyl sulfateDibenzanthraceneNitrosamineDiepoxybutane3-methyl cholanthrineVinyl chlorideAnticancerous drugsAromatic aminesNickel1-acetyl imidazoleAmidesChromiumDimethyl carbamyl chlorideAzo dyesInsecticides BenzidineFungicides a-naphthlaminePolychlorinated biphenyls Aflatoxin B1 Griseofulvin Betel nuts Safrole Cycasin 