  A graph $G$ is \emph{$(a,b)$-choosable} if given any list assignment $L$ with
$|L(v)|=a$ for each $v\in V(G)$ there exists a function $\varphi$ such that
$\varphi(v)\in L(v)$ and $|\varphi(v)|=b$ for all $v\in V(G)$, and whenever
vertices $x$ and $y$ are adjacent $\varphi(x)\cap \varphi(y)=\emptyset$. Meng,
Puleo, and Zhu conjectured a characterization of (4,2)-choosable graphs. We
prove their conjecture.
