Finish the following sentence with the best choice: To open a letter very neatly without ruining the envelope when you don't have a letter opener,

Choices:
- stick your finger under the edge of the back flap and pull up along the top fold.
- stick a knife under the edge of the back flap and pull up along the top fold.

Answer:
stick a knife under the edge of the back flap and pull up along the top fold.