Correct option is B
Given - 3, 20, 121, 604, 2417, ?
Logic = Continuous multiplication with 7, 6, 5, 4 --- so on with subtraction 1 and addition 1 alternatively.
3 ×7 - 1 = 21 - 1 = 20
20 ×6 + 1 = 120 + 1= 121
121 ×5 - 1 = 605 - 1= 604
604 ×4 + 1 = 2416 + 1 = 2417
2417 ×3 - 1 = 7251 - 1= 7250
hence correct missing term is 7250