What button is pressed to reset the scale to zero with the cup on it?

The correct choice for resetting the scale to zero with the cup on it is the tare button. In the context of scales, the tare function is specifically designed to subtract the weight of the container (in this case, the cup) from the total weight measured by the scale. When the tare button is pressed, it effectively zeroes out the scale's reading, allowing the user to measure only the weight of the substance being added without including the weight of the cup itself.

This function is crucial in scenarios like culinary measurements, laboratory settings, or any situation where precise measurement of a component is required without the added weight of the container. By using the tare feature, you can ensure accurate measurements, facilitating better results in your tasks.