Note
The wording of the title may be a bit vague, but I'm not asking if CFLs are closed under reversal. Please see below.
Problem Description
Given a word $w$, define $w^{r}$ to be its reversal.
Let $L=\{ G \vert G \text{ is a } CFG \text{ and for every } w \in L(G), w^{r} \in L(G) \}$
Prove that $L$ is undecidable.
My Attempt
I am aware that I should reduce a known-to-be-undecidable language to L, but by looking at the four undecidable languages here (Equivalence, Disjointness, Containment, Universality), I still failed to determine which language I can use. Please guide me a direction, thank you.