In the following passage some of the words have been deleted. Read the passage carefully and select the correct answer for the given blank out of the four alternatives.

In Switzerland these glacial meltwater are (1)_______ for hydropower. In fact, water on 93% of Switzerland ultimately passes (2)______ at least one electric plant before even (3)__________ the country. So one consequence is that melting glaciers help to (4)_________ for low rainfall in times of drought, filling reservoirs to supply the nation's (5)______ supply.

Select the most appropriate option to fill in the blank no. 2.

through

- In the blank, "In fact, water on 93% of Switzerland ultimately passes (2)______ at least one electric plant..."., the suitable word is through.

- The word "through" is used in the blank because it conveys the idea of movement or passage from one point to another. In this context, it implies that the water in Switzerland flows through or passes through at least one electric plant.