Why is andorra's water supply important to the country? for commerce for electricity for navigation for recreation

Andorra is landlocked and has only a small amount of rivers, which are not really their main means of transportation, so it's not for navigation or commerce. It's also not famous for its water sports.

However, 40% of Andorra's electricity comes from its hydroelectric dam! so the correct answer is "electricity"

It is c. naturally in the environment