Which situation is an example of opposite quantities combining to make 0? A gift card had a balance of $20. Then, all $20 on the gift card was spent.

A swimmer was 6 feet below the surface of the water. Then she descended another 6 feet.

A container had 2.1 ounces of liquid. Then, 2.1 ounces of liquid was added to the container.

The temperature was - 5 degrees Fahrenheit. Then, the temperature decreased by 5 degrees.