The correct option is B 28G
1) Number
In first row, 3×9=27(middle number)
In second row, 7×3=21(middle number)
In third row, 4×7=28(middle number)
2) Letter
In first row, C→D→E (Difference is ′0′ letter)
In second row, I→K→M (Difference is ′1′ letter)
In third row, D→G→J (Difference is ′2′ letters)
Hence, option B is the correct answer.