A river that comes from rain, glaicers etc would be a good example of fresh water rivers. Cause the water is coming from something that is most likely been unthouched by man or has been filterd and cleaned from minerals in the ground.
An example i can think of is...
the amount of salt present in human cells cytoplasm suggests we evolved from species in the sea
Both a b c are the right answer choice for this question
B. <span>The thesis statement is the answer to the research question</span>