Select the option that represents the letters that, when placed from left to right in the following blanks, will complete the letter-series.
A S D F _ A _ _ F G _ U D _ G A _ _ F G

Correct option is A

Given series,
A S D F _ A _ _ F G _ U D _ G A _ _ F G
From option (a) GTDAFVD
A S D F G / A T D F G / A U D F G / A V D F G in the series S → T → U → V are increase and remaining letters are same.
Thus, the correct answer is (a).