D
Climatologist: Over the coming century, winter temperatures are likely to increase in the Rocky Mountains due to global warming. This will cause a greater proportion of precipitation to fall as rain instead of snow. Ttherefore, the mountain snowpack will probably melt more rapidly and earlier in the season, leading to greater spring flooding and less storable water to meet summer demands. Which one of the following, if true, most strengthens the climatologist's argument?
A: Global warming will probably cause a substantial increase in the average amount of annual precipitation in the Rocky Mountains over the coming century.
B: On average, in the regions of the world with the mildest winters, there is more spring flooding and less storable water than in regions of the world with much colder winters.
C: The larger a mountain snowpack is, the greater the amount of spring flooding it is likely to be responsible for producing.
D: In other mountainous regions after relatively mild winters, the melting of snowpacks has led to greater spring flooding and less storable water, on average, than in those mountainous regions after colder winters.