Select the combination of letters that when sequentially placed in the blanks of the given letter series will complete the series. _ _m_ogng_ _no_ _ggm

gnggmgn ggngmgn ngngmgm gmngmgn

ggngmgn

The given series is:- ggmnogn / ggmnogn / ggm Required code will be: ggngmgn