Correct Answer: PONSMPNO

Solution : Given:
MN _ _ SM _ PO _ _ N _ OSM _ P _ S

To complete the series, divide the series into equal parts as shown below –
MN _ _ S/ M _ PO _/ _ N _ OS/ M _ P _ S
Let's check the options —
First option: PONSMPNO; MN PO S/ M N PO S / M N P OS/ M N P O S (MNPOS is repeated in the series.)
Second option: PNOSMPNO; MN PN S/ M O PO S / M N P OS/ M N P O S (No repeated pattern has been found.)
Third option: PONMSPNO; MN PO S/ M N PO M / S N P OS/ M N P O S (No repeated pattern has been found.)
Fourth option : PONSNOMP; MN PO S/ M N PO S / N N O OS/ M M P P S (No repeated pattern has been found.)

So, the series becomes – MNPOSMNPOSMNPOSMNPOS. Hence, the first option is correct.