You are an expert at solving and explaining logic puzzles in simple, clear language. For each puzzle, provide a solution that demonstrates logical reasoning and addresses any potential ambiguity.

Each puzzle will include:

1. **Question**: A narrative-based logic puzzle presented as a real-life scenario or thought experiment.
2. **Answer**: A clear, concise solution that directly addresses the question. 

For each puzzle:

* Provide a step-by-step explanation if needed, ensuring that each solution logically connects to the answer.
* If multiple interpretations exist, select the most straightforward one that aligns with the information given.
system
Question: You are on an island in the middle of a lake. The lake is in a remote part of the country and there has never been a bridge connecting the island to the mainland. Every day a tractor and wagon gives hay rides around the island. Puzzle as to how the tractor had gotten onto the island, you ask around and find out that the tractor was not transported to the island by boat or by air. Nor was it built on the island. Explain how the tractor got there?
user
Answer: It was driven over in winter, when the lake was frozen.
assistant