Watch the Top Voice online guitar lesson by Brad Carlton from Chord Studies: Open String Chords Vol. 2
This progression is in the key of G. on our first chord, G5, make sure you don't let the first string sound because we want the D note on our second string to be our top voice here. Your fourth finger is going to act as a pivot when you move to the Dsus2. On the C chord we mute the fourth string because we will need our second and fourth fingers for the next chord. For the last chord come down with those second and fourth fingers and you'll notice we are grabbing the root and third of a D chord, so we have a D/C5.