A meeting was attended by the representatives of 25 countries during the 1880s. Its main aim was to establish an origin of the imaginary vertical lines that run around the Earth. Which meeting is being referred to here and where was it held?

The correct option is C The International Meridian Conference, Washington.
Although latitude was always measured from the Equator, there was no equivalent point of reference for longitude. The International Meridian Conference was held on on 1 October, 1884, to adopt a single common meridian. In this conference, Greenwich in London was made the reference point for longitudes. It was named as the Prime Meridian. It was also decided that the longitudes would be calculated eastwards and westwards from the prime meridian upto 180°.