Which of the following reaction can be employed for getting unsymmetrical alkanes in good yield ?

Corey-house reaction :

${\mathrm{R}}_2\mathrm{CuLi}+\mathrm{R}\text{'}-\mathrm{X}\to \mathrm{R}-\mathrm{R}\text{'}+\mathrm{R}-\mathrm{Cu}+\mathrm{LiX}$

This is the best method for the preparation of unsymmetrical alkanes when compared with Wurtz reaction.