Concept:The series decreases by a constant amount each time.Explanation:The given terms are 100,75,50,25,0.Each term is obtained by subtracting 25 from the previous term.So, the term before 100 must be 100+25=125.Check: 125,100,75,50,25,0 follows the same pattern.Answer:The missing term is 125.Hence, the correct option is D.