Tanner felt his eyes grow heavier as he held back a yawn. His math teacher said, "Tanner, can you do this problem?" Tanner stared at the board, his mind in a fog.

Based on the text, which sentence is most likely to be true?
a: tanner is eager to answer the question
b: tanner likes math class
c: tanner is having trouble staying awake

c: Tanner is having trouble staying awake