Finish the following sentence with the best choice: How can I set aside 500 dollars, a bit at a time?

Choices:
- Place spare twenties in a 2 liter bottle, the volume of 2 liters equal 500 dollars in twenties.
- Place spare dimes in a 2 liter bottle, the volume of 2 liters equal 500 dollars in dimes.

Answer:
Place spare dimes in a 2 liter bottle, the volume of 2 liters equal 500 dollars in dimes.