1-Bromobutane is treated with 2 equivalents of lithium metal in dry ether to give $\mathrm{X}$. Two equivalents of $\mathrm{X}$ react with $\mathrm{CuI}$ to give the Gilman reagent $\mathrm{Y}$, and $\mathrm{Y}$ then reacts with $\mathrm{CH}{}_3\mathrm{I}$ to give the hydrocarbon $\mathrm{Z}$. $\mathrm{Z}$ is

1. Apentane
2. Boctane
3. Chexane
4. Dbutane