Select the letter -cluster from among the given options that can replace the question mark (?) in the following series.
FPW, EQV, DRU, ?

Option
a) COS
b) CST
c) TWX
d) CSG

Solution

F P W, : 6 – 16 – 23
E Q V, : 5 – 17 , 22
D R U : 4 – 18 – 21

First letter is Decrease 1
2nd Letter Increase 1
3rd letter Decrease 1
Follow same logic to get next word:
3 – 19 – 20 = C S T

Answer: CST