Finish the following sentence with the best choice: How can you keep from marking your wall with doorknobs hitting it?

Choices:
- Place a tennis racket on the knob so that it will guard the wall from the knob edge.
- Place a tennis ball on the knob so that it will guard the wall from the knob edge.

Answer:
Place a tennis ball on the knob so that it will guard the wall from the knob edge.