Answer: Option(b)
Explanation:
The reason for including the 3 percent of freshwater as most useful in the importance of freshwater ecosystems is, almost 70 percent of earth`s surface is occupied by water. In that only 3 percent is freshwater.
Out of overall value 2 percent of freshwater is held up in glaciers and formed as ice at both poles of North and South. The 1 percent remaining is mostly groundwater, fills the world's aquatic ecosystems like lakes and rivers, ponds, streams, springs,, and wetlands .
