Which of the following is a geometric series?

A geometric series has a constant ratio between consecutive terms. In D, each term is multiplied by 7: 14 ÷ 2 = 7, 98 ÷ 14 = 7, and 686 ÷ 98 = 7. The other choices do not have a constant ratio, so 2 + 14 + 98 + 686 is geometric.

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