Finish the following sentence with the best choice: How to thicken tomato sauce without changing the flavor?

Choices:
- Once the tomato sauce has come together, reduce it by increasing the heat and leaving the lid off the pot until it is about one fifth less
- Before the tomato sauce has come together, reduce it by lower the heat and leaving the lid on the pot until it is about one fifth less

Answer:
Once the tomato sauce has come together, reduce it by increasing the heat and leaving the lid off the pot until it is about one fifth less