Take a look at the item again:
One day in class, Shantrell rested her head against the
wall (A)
and discovered (B)
that she could hear the classical music that Mr. Nguyen played in
his office on the other side. (C)
The music promptly put her to sleep.
You wanted to do this:
One day in class, Shantrell rested her head against the wall and discovered
that she could hear the classical music that Mr. Nguyen played in his office
on the other side. Which promptly put her
to sleep.
Replacing The music with which makes a fragment. Which introduces a subordinate clause that cannot stand alone as a complete sentence.
You might want to review the rules.
Go back to the sentence to try again.