Recently, the term "pumped-storage hydropower" is actually and appropriately discussed in the context of which one of the following?

1. A

   Irrigation of terraced crop fields

   Terraced irrigation. Pumped storage is not that.

2. B

   Lift irrigation of cereal crops

   Lift irrigation of cereals. Different pumps, different purpose.

3. C

   Long duration energy storage

   Long-duration energy storage. Pump up when power is cheap; generate when it is scarce.

4. D

   Rainwater harvesting system

   Rainwater harvesting. Not pumped-storage hydro.

Summary. Official key is (c). Pumped-storage hydropower moves water between two reservoirs to store electricity for hours to days — long-duration energy storage. It is not an irrigation or rainwater-harvesting scheme.