Addition of HBr to 1-butyne (\(CH\equiv C-CH_2CH_3\)) follows Markovnikov's rule. First equivalent of HBr gives 2-bromobutene (vinyl bromide). With excess HBr, the second addition also follows Markovnikov's rule, adding to the more substituted carbon: the major product is 2,2-dibromobutane (\(CH_3CBr_2CH_2CH_3\)). Note: the paper lists option (C) as 2,2-Bromobutene which corresponds to 2,2-dibromobutane.