Select the combination of letters that when sequentially placed in the blanks of the given letter series will complete the series. a c _ d a _ d d a _ _ d a c _ d

d c c d d a c d c a d a c c d c c d a d

d c c d d

a c _ d a _ d d a _ _ d a c _ d The logic followed here is : a c d d / a c d d / a c d d / a c d d Hence  'd c c d d' is correct answer