A
Commentator: Although the present freshwater supply is adequate for today' s patterns of water use, the human population will increase substantially over the next few decades, drastically increasing the need for freshwater. Hence, restrictions on water use will be necessary to meet the freshwater needs of humankind in the not-too-distant future. Which one of the following is an assumption required by the argument?
A: The freshwater supply will not increase sufficiently to meet the increased needs of humankind.
B: Humans will adapt to restrictions on the use of water without resorting to wasteful use of other natural resources.
C: The total supply of freshwater has not diminished in recent years.
D: No water conservation measure previously attempted yielded an increase in the supply of freshwater available for human use.