What theme is suggested by this passage from the excerpt from The Grapes of Wrath?
To California or any place—every one a drum major leading a parade of hurts, marching with our bitterness.
A. Bitterness is never the answer to one's troubles.
B. We can escape bitterness if we go to new places.
C. People need to rise above their petty problems.
D. Everybody carries personal pain throughout life.