Which reagent converts the compound shown into the corresponding primary alcohol?

The compound is butanoic acid. Only the strong hydride donor $\mathrm{LiAlH}{}_4$ reduces a carboxylic acid to butan-1-ol. $\mathrm{NaBH}{}_4$ is too weak, Clemmensen reduction ($\mathrm{Zn}(\mathrm{Hg})$/HCl) targets ketones and gives alkanes, and Pd/C with $\mathrm{H}{}_2$ does not reduce a carboxyl group under mild conditions.