Which summer ceremony at the Tower of London, dating from the fourteenth century, involves the Yeoman Warders locking the main gates with a formal ritual?

• A Changing of the Guard
• B Ceremony of the Keys ✓
• C Beating Retreat
• D Gun Salute

The Ceremony of the Keys has been performed every night for over 700 years without fail; the Chief Yeoman Warder locks the gates at exactly 9:53 pm each evening.