.Set up with an Am chord, add 4th finger to the 3rd fret to make your sus4 and whilst playing the arpeggio pattern you use the B string to drop through sus4, minor, sus2.
The dropping along the B string continues throughout the piece as you change the chord underneath it.
Am
E [--------0-----------0-----------0------------------
B [--------------3-----------1-----------0------------
G [-----------2-----2-----2-----2-----2-----2-----2---
D [-----2--------------------------------------2------
A [--0------------------------------------------------
E [---------------------------------------------------
Em
E [--------0-----------0-----------0------------------
B [--------------3-----------1-----------0------------
G [-----------0-----0-----0-----0-----0-----0-----0---
D [--------------------------------------------2------
A [-----2---------------------------------------------
E [--0------------------------------------------------
C
E [--------0-----------0-----------0------------------
B [--------------3-----------1-----------0------------
G [-----------0-----0-----0-----0-----0-----0-----0---
D [------2-------------------------------------2------
A [--3------------------------------------------------
E [---------------------------------------------------