A duck-billed lock breaker is used to:

A duck-billed lock breaker is specifically designed to displace a lock cylinder, which allows for more efficient opening of padlocks without causing excessive damage. When using this tool, the duck-billed design provides leverage and precision needed to manipulate the lock mechanism effectively. The tool's shape enables it to apply force evenly across the lock, facilitating a clean and quick removal or opening of the lock.

In the context of the other choices, while the duck-billed lock breaker can be used to assist in opening various types of locks, its main function is most directly aligned with padlocks. Other options include techniques and tools specific to different types of locks or windows, which do not utilize the unique design and purpose of the duck-billed lock breaker.