Which sequence is an arithmetic progression with (d=-2)?

Correct answer: (18, 16, 14, 12, \ldots)

In an arithmetic progression, the difference between consecutive terms must remain constant. In option B, \(16-18=-2\), \(14-16=-2\), and \(12-14=-2\), so its common difference is \(d=-2\). Option A has a difference of \(+2\), the terms in option C are doubling, and option D has differences \(-2,-3,-4\). Exam tip: subtract each term from the next one and check whether the difference is constant.