Select the combination of letters that when sequentially placed in the blanks of the given series will complete the series. d _ a _ b _ q d h _ a _ c q _ h _ a _ c q |
h a c a b d a b h a b a b d a b h a c a b d q b h a q a b d a b |
h a c a b d a b |
d h a a b c q / d h a a b c q / d h a a b c q h a c a b d a b |