analytical chemistry - What is the proton NMR spectrum of p-methoxyphenol?

I think there will be two pairs of doublets, since the hydrogens adjacent to the $\ce{OCH3}$ and those adjacent to the $\ce{OH}$ group will be in different environments. The answer, however, is that there'll be a singlet for 4 Hydrogens.

To give some context, I am extremely unused to the proton NMR of benzene derivatives, and any (introductory) links telling me a bit about it would be appreciated. I'm aware of the theory behind NMR spectrosocopy, the 'n+1' rule, and the ways to tell if two Hydrogens are magnetically equivalent.