I'll give you a question, please answer with step-by-step reasoning process. Where would you find a metal rod in most people's preferred method of transportation?
Options:
- airplane
- construction site
- shops
- engine
- broken bone

Show your work and conclude with the exact phrasing "Therefore, the final answer is [answer]." where [answer] is just the final number or expression that solves the problem.
user
Engine is one of the most prefferd mode of transportation. Engines have rods in them as they are heavily made of metals.
The answer: engine.