Q: Given a scientific passage and an answer, generate a question for the given answer.
Passage: Magnetism is the ability of a material to be attracted by a magnet and to act as a magnet. No doubt you've handled refrigerator magnets like the ones in Figure below . You probably know first-hand that they stick to a metal refrigerator but not to surfaces such as wooden doors and glass windows. Wood and glass aren't attracted to a magnet, whereas the steel refrigerator is. Obviously, only certain materials respond to magnetic force. Answer: magnetic
A:
Unlike wood and glass, steel is an example of a material that responds to what force?