Which statement about combination locks is true?

• A. They are only padlocks.
• B. They require a physical key to operate.
• C. A combination lock can be a built-in lock or a padlock.
• D. They never use a dial.

Answer: (C)

A combination lock is unlocked by entering a specific sequence of inputs, such as numbers on a dial or buttons, rather than by turning a physical key. This type of input method can be built into a device or fixture (a built-in lock) or exist as a separate, portable device (a padlock). That makes the statement true: a combination lock can be either built-in or a padlock.

The other ideas aren’t accurate because combination locks aren’t limited to one form. They aren’t only padlocks, since you can have combination locks integrated into safes, lockers, or doors. They don’t always require a physical key—entering the correct combination suffices. And they can indeed use a dial, as traditional mechanical combination locks rely on turning a dial to input the sequence, so saying they never use a dial isn’t correct.