HELP Read the excerpt from "Object Lesson, Part 2."

He leaned against Louise's desk, forcing himself to relax.

It was these "simple" problems. Nothing big and important like murder, blackmail, bank robbery. A miserable seven dollars lifted by a teenage delinquent in an overcrowded classroom . . .

He thought furiously.

Let the bell ring at 9:35 and the boy strut out of Miss Carpenter's room undetected, with his loot, and he would send up a howl like a wolf cub over his first kill.

What inference does Ellery make?

A. that he may pass out if he does not stop and relax

B. that there are harder problems to solve in the world

C. that the thief would not have committed the crime if there weren't so many students in the class

D. that the thief has no idea that Ellery is aware of his plans to steal the seven dollars.