A substance that vigorously reacts with most metals to produce hydrogen, readily conducts electricity, turns litmus red, and has a pH less than 7; typically corrosive or sour-tasting. A: suspension
B: base
C: acid
D: colloid

C. Acid

Explanation:

If you have chemistry classes and performed experiments regarding acids and bases, you would physically tell it's acid if the lithmus paper turned red and base if it turned blue. Also, in the pH level chart, there are only two characteristics--acidic and basic. Since it has less than 7 pH, it is definitely acid. Plus, remember the taste of some vitamin C tablets? It has a sour taste to it, isn't it? This is because of ascorbic acid.

c because the action was the roller coaster reaches bottom of hill (action) reaction would be blood tends to drain away from head

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