Select the Letter Cluster that can replace the question mark (?) in the following series.
MOND, RUUL, WABT, BGIB, ?

Given Series : 

MOND, RUUL, WABT, BGIB, ?

The pattern followed here is : 

• Difference between Place values of the first alphabets of given word in series is 5.
• Difference between the place values of the second alphabets  of given words in the series is 6
• Difference between the place value of the third alphabets of given words in the series is 7.
• Difference between the place vaues of the forth alphabets of given words in the series is 8. 

Therefore, The word which will replace the ? is : 

B + 5 = 2 + 5 = 7 = G

G + 6 = 7 + 6 = 13 = M

I + 7 = 9 + 7= 16 = P

B + 8 = 2 + 8 = 10 = J

Hence, option D is correct.