Concept:The series combines two independent alphabetical patterns: first letters decrease by one step, and second letters increase by one step.Explanation:The first letter of each term follows Z, Y, X — each moves one step backward.The second letter of each term follows A, B, C — each moves one step forward.Therefore, the next first letter is W (after X), and the next second letter is D (after C).So the next term is WD.
