Finish the following sentence with the best choice: How do I clean Out the Inside of the Bamboo?

Choices:
- 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.
- 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:
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.