In the following question, which one set of letters when sequentially placed at the gaps in the given letter series shall complete it ? MN_O_NN_M_NO

Answer: B. NMON

Official answer key verified. Detailed explanation coming soon.

Source: SSC CHSL (Tier-1) 2016 Online Exam Paper held on 11 January 2017, Evening Shift (General Intelligence) — SSC-published paper with official answer key, via sscportal.in (note: image files on the Quantitative Aptitude page are named 08-Jan-2017, likely an sscportal upload-label error; page titles and QID sequence 201-300 consistently indicate 11 Jan 2017 Evening Shift) · official-answer-key