So here we have an example problem that asks, in which of the following aquatic biomes would you expect to find organisms that can tolerate both saltwater and freshwater? And we've got these four potential answer options down below. Now, of course, the aquatic biome that we might expect to have organisms that can tolerate both saltwater and freshwater would be the aquatic biome that has both freshwater and saltwater. And, of course, we know from our last lesson video that estuaries are somewhat of a unique aquatic biome because they contain both freshwater and saltwater, since an estuary is where a river meets an ocean, and the river has freshwater, whereas the ocean has saltwater. And so the mixture of the two gives it both, freshwater and saltwater, and so we would expect to find organisms there that can tolerate both.

And so we can indicate the answer option B, estuaries, is the correct answer to this example problem. Now option A says lakes, but recall from our previous lesson videos that lakes are defined as stationary bodies of freshwater surrounded by land. And so most of these lakes are going to have freshwater, so we can eliminate that option because we wouldn't expect to find organisms that can tolerate high salt concentrations in most lakes. Option D says streams, and again, we know that streams and rivers contain freshwater, so we can eliminate option D for a similar reason. And then option C says riverine wetlands, which we did not cover in our previous lesson videos.

We did talk about wetlands, but riverine wetlands are just wetlands that are found along rivers. And, again, we know that rivers contain freshwater, so we can eliminate option C. So, again, B here is the correct answer, and I'll see you all in our next video.