"R. W. and Melvin," whispered T. J., "they hurt me bad." He looked up, expecting sympathy. But our faces, grim behind the light Stacey held, showed no compassion. T. J.'s eyes dimmed, then, undoing the buttons to his shirt, he pulled the shirt open and stared down at his stomach. —Roll of Thunder, Hear My Cry,
Mildred D. Taylor

Which words from the passage indicate that the tone is serious?

“hurt me bad”
“he pulled”
“his stomach”
“shirt open”