Read the following passage: Some chord shapes are movable. Let's experiment by moving the E-chord shape up the fretboard. Begin by playing an E major chord, and then move up the fretboard one fret at a time. Each finger in the E-chord shape serves as a guide finger maintaining contact with its string when the left hand is moving up or down the fretboard. Based on what you've read, which of the following could you assume is true? All chord shapes are movable. Every chord change in every song uses guide fingers. Guide fingers can be useful when changing between chords. Guide fingers serve no purpose.