The odd one out is C. DGJ.
The other options, A. BEH, B. CFI, D. EHL, and E. FIL, all have the same number of letters. C. DGJ has 3 letters, while the others have 4 letters.
A. BEH has 3 letters: B, E, and H. B. CFI has 4 letters: C, F, I, and H. D. EHL has 4 letters: E, H, L, and H. E. FIL has 4 letters: F, I, L, and L.
