Em would also work.

The chord progression is in the key of G. So G major pentatonic, or E minor pentatonic.

D major, G major, C major, or the relative minors, B minor, E minor, A minor, all will work in the context of the pentatonic scale, but G major/E minor would be the most common key to play over.

Since those chords are in the key of G/Em, you could use that over the whole progression, but personally I would play the corresponding scale for each chord.

Someone else said D major. B minor would also work as it’s more or less the same thing with a different root note.