Riddle

I bear the weight of knowledge on my shoulders every day. You'll find me full at dawn and lighter by the hallway. What am I?

Choose an answer

A.A locker
B.A desk
C.A notebook
D.A backpack
Hint: It's a 2-word phrase with 9 letters, starting with "A".

Answer

A backpack

Why this is the answer

Students carry their books in it; it gets lighter as books are used.

This riddle is filed under Hard/Difficult Riddles and rated Medium.