The correct option is C J, F
The given sequence is a combination of two series :
I. 1st, 3rd, 5th, 7th, 9th, 11th terms i.e. A, B, C, D, E, ?
II. 2nd, 4th, 6th, 8th, 10th terms i.e. B, D, F, H, ?
Clearly, series I consists of consecutive letters while series II consists of alternate letters. So, the missing letter in I is F, while that in II is J. So, the missing terms i.e. 10th and 11th terms are J and F respectively.