The unit rates which will be reasonable for Violet to use to describe how fast the sand is draining from the upper portion to the lower portion of the glass is cubic centimeters per minute.
Explanation:
As the first 2 options gallons per hour and liters per hour, these denote liquid forms. But sand is not liquid that is why it cannot be the answer.
Cubic inches per second is very fast as compared to the small hourglass and the amount of sand that could be present in it. Moreover one side of the hourglass needs to be emptied in 24 hours, so this option is also not possible.
