Question

Broken pieces of an item that has been destroyed usually are referred to as _______.

Answer 1

A. Debris.
Example - "The tornado that passed through left a lot of debris around the town. They spent all day picking it up." 
Debris is often used to describe weather damages, mainly tornadoes because they rip pieces of buildings and other architectural structures causing a lot of debris. 

Answer 2

I agree with the person above - Broken pieces of an item that has been destroyed usually are referred to as A. debris.