Finish the following sentence with the best choice: How to use a rock as an anchor?

Choices:
- Place large rock into cloth bag, attach rope to bag and throw overboard.  Tie off rope to boat to anchor.
- Place large rock into thin plastic bag, attach rope to bag and throw overboard.  Tie off rope to boat to anchor.

Answer:
Place large rock into cloth bag, attach rope to bag and throw overboard.  Tie off rope to boat to anchor.