Finish the following sentence with the best choice: To make your free standing bookshelf more stable.

Choices:
- Attach a premeasured sheet of plywood to the back of the bookshelf using a hammer and nails.
- Attach a sheet of plywood to the back of the bookshelf using a hammer and nails.

Answer:
Attach a premeasured sheet of plywood to the back of the bookshelf using a hammer and nails.