What is the common ratio of the given geometric sequence? 625,125,25,5,1,...

Find the common ratio by dividing a term by the one before it: 125 ÷ 625 = 1/5. The next pair confirms it: 25 ÷ 125 = 1/5. So the common ratio is 1/5, which is choice C, 25 over 125.

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