Muscle contractions in your lower legs act as pumps, and elactic vein walls help blood return to your heart. Tiny valves in your veins open as blood flows toward your heart then close to stop blood from flowing backward. Causes of varicose veins can include: Age
I believe none of these options are correct. However, if you had to choose one, I would pick A - <span>Nina slid into her seat just as the bell rang and tried to catch her breath.
B, C, and D are incorrect because these are all examples of direct characterization, meaning that the other directly tells us what these people are like. This doesn't happen in A, which is why I would choose that option.
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