Please choose the correct solution to the question: How do I clean Out the Inside of the Bamboo?

Solution1: Using a half round file inserted into the hollow in the center of the bamboo and move it up and down while going around inside until the inside is smooth.

Solution2: Using a nail file inserted into the hollow in the center of the bamboo and move it up and down while going around inside until the inside is smooth.

Answer format: solution1/solution2
Answer: solution1