1). photosynthesis;
2). gills;
3). rivers;
4). blood;
5). solutes;
6). lungs;
7). streams;
8). carbon transfer;
Given those answer options, answer the question: Fact 1: Gills are used for breathing water by aquatic animals. Fact 2: Animals breathe in oxygen and breathe out carbon dioxide. Given the two facts above, how do aquatic animals get oxygen?
A:
2).