Complex sentence: For the second disc Felix Pappalardi chose "Traintime" because it featured Jack Bruce performing a harmonica solo, and "Toad" because it features Ginger Baker's drumming while "Spoonful" and "Crossroads" were used to showcase Eric Clapton's guitar-playing.
Split into simpler sentences: For the second disc Felix Pappalardi chose "Traintime" because it featured Jack Bruce performing a harmonica solo. The songs "Spoonful" and "Crossroads" were used to showcase Eric Clapton's guitar-playing.