Answer : Option C
Explanation :
The given sequence is a combination of three series:
I: 1st, 4th, 7th terms i.e., 2, 4, 9.....
II: 2nd, 5th, 8th terms i.e.,3, 6, 12.......
III: 3rd, 6th, 9th terms i.e., 4, 8, 16..................
In each one of I, II and III, each term is twice the preceding term.
So, 9 is wrong and must be replaced by (4 × 2) i.e., 8.