So here we have an example problem that says, given the information from this graphic and the previous lesson, which of the following processes moves the smallest volume of water? And we've got these 4 potential answer options down below. Now taking a closer look at this graphic over here, notice that the full circle here represents all of Earth's water. And notice that 97% of all of Earth's water is salt water that falls in the oceans, and only 3% of Earth's water is fresh water, represented as this tiny sliver. And so notice answer option b says evaporation from oceans, which again accounts for the vast majority of Earth's water.

So that's going to be moving a relatively large amount of water, not the smallest volume of water. So for that reason, we can eliminate answer option b. And for a similar reason, we can also eliminate answer option d, which says precipitation over oceans. Oceans are so vast that they're going to receive a lot of precipitation. So we can eliminate answer option d.

So now we're between either option a or option c. Notice option a says evaporation from freshwater rivers and lakes, and option c says evapotranspiration over the land. Now, taking a closer look at this breakdown of the freshwater that we can see right here, notice that almost 70% of the freshwater is locked up in glaciers and snow. 30% of the freshwater is actually groundwater, such as aquifers, soil moisture, and permafrost. And less than 1% of the freshwater is actually lakes and rivers, which is just mind-blowing to think about.

But what we're saying here is that evaporation from freshwater rivers and lakes is going to represent a very small fraction of the water volume being moved. And, evapotranspiration is a term that encapsulates both evaporation and transpiration. So evapotranspiration includes the evaporation from freshwater rivers and lakes, but it also includes transpiration or water release from plants. And so evapotranspiration will move larger volumes of water than just evaporation on its own. And so for that reason, we can eliminate answer option c because it will move a larger volume of water than answer option a, which means option a moves the smallest volume of water amongst these options.

So, a here is the correct answer, and that concludes this example problem. So I'll see you all in our next video.