a
(a) \(C{H_3} - C{H_2} - C{H_2} - C{H_3} \xrightarrow[475\, K]{H_2SO_4}\) \(\mathop {C{H_3} - CH = CH - C{H_3}}\limits_{{\rm{More \,symmetrical\,}}\,({\rm{major}}\,{\rm{\,product)}}} \)

\(C{H_3} - C{H_2} - C{H_2} - C{H_3}\xrightarrow[{475\,K}]{{{H_2}S{O_4}}} \)\(\mathop {C{H_2} = CH - C{H_2} - C{H_3}}\limits_{{\text{Less}}{\mkern 1mu} {\text{symmetrical}}{\mkern 1mu} {\text{or}}{\mkern 1mu} {\text{unsymmetrical}}{\mkern 1mu} ({\text{minor}}{\mkern 1mu} {\text{product}})} \)

It is based on Saytzeff's rule. According to this more symmetrical or more alkylated alkene predominates.