The Development Monitoring and Evaluation Office (DMEO) was constituted on

The correct answer is (A) 18 September 2015.

• The Development Monitoring and Evaluation Office (DMEO) was constituted on 18 September 2015 by the Government of India through a resolution to replace the erstwhile Programme Evaluation Organization (PEO).
• DMEO is an attached office under the NITI Aayog, tasked with monitoring the progress of various government schemes, projects, and policies to ensure transparency, accountability, and efficiency in public service delivery.
• The office functions under the guidance of the NITI Aayog to provide technical support and foster a data-driven evaluation culture; the other dates provided in the options do not correspond to the establishment of this specific organizational body.