The correct answer is C.3,9,27,81,…

A geometric progression is a sequence of numbers in which each term after the first is found by multiplying the previous term by a fixed, non-zero number called the common ratio. In option A, the common difference between consecutive terms is 2, which means it is an arithmetic progression, not a geometric progression. In option B, the common difference between consecutive terms is not constant, so it is also not a geometric progression. Option C, however, has a common ratio of 3, as each term is obtained by multiplying the previous term by 3. Therefore, option C is the correct answer. Option D is not a valid option as it does not provide a sequence.