Select the combination of letters that when sequentially placed from left to right in the blanks of the given series will complete the series.

_om_onm_mnon_omn_n

By Trial and Error method,

Option A

nommon | momnon | momnnn

The above letters do not form a series. Hence option A is incorrect.

Option B

nomnon | mmmnon | momnon

The above letters do not form a series. Hence option B is incorrect.

Option C

momoon | momnon | momnmn

The above letters do not form a series. Hence option C is incorrect.

Option D

momnon | momnon | momnon

The above letters form a series.

Hence, the correct answer is Option D