If isopropyl chloride and propyl chloride both react with $\mathrm{Na}$ in dry ether, which alkanes are obtained?

(a) $\mathrm{CH_3CH(CH_3)CH_2CH_2CH_3}$ ($2$-methylpentane)
(b) $\mathrm{CH_3CH(CH_3)CH_2CH_3}$ ($2$-methylbutane)
(c) $\mathrm{(CH_3)_2CHCH(CH_3)_2}$ ($2,3$-dimethylbutane)
(d) $\mathrm{CH_3CH_2CH_2CH_2CH_2CH_3}$ ($n$-hexane)