Answer:
B. The pie graph represents 100 percent of the world's water supply.
Step-by-step explanation:
Pie graphs are circular graphs used to present statistic data. Each data is presented on pie graph in different color so that sum of all data percentages fills the whole surface of the circle, or 100%.
From the title of the pie graph (World's Water Supply) we can see what it represents. Each color on the graph shows different source of water (97% of water supply comes from salt water in seas and oceans, 2% from polar ice and 1% from free circulating water). All these percentages add up to 100%.