Correct option is D
B A __ D L __ A M __ L B A __ F L B A __ G L
Logic: We have to put each option in the blank space when any option gives us a proper logical series that will be correct option.
From option (a):MCEMM
B A M D L C A M E L B A M F L B A M G L (not follows logical pattern)
From option (b):MMMCL
B A M D L M A M M L B A C F L B A L G L (not follows logical pattern)
From option (c):MBMBL
B A M D L B A M M L B A B F L B A L G L (not follows the logical pattern)
From option (d):MBEMM
B A M D L/ B A M E L /B A M F L /B A M G L (follows logical pattern)
4th letter increasing by 1 place.
Thus, correct option is (d).