Which one of the following best explains how gunpowder was the nemesis of traditional castles?

• A. Wars were fought with guns and hiding in castles was no longer necessary.
• B. Artillery forts with large cannons became more stylish than traditional castles.
• C. Defending castles grew difficult since attackers could just shoot castle defenders.
• D. Cannons were able to knock down stone walls, so castles offered little protection.