If the standard time of a country is GMT + 1hr, which longitude's local time is adopted by the country?

The standard time of a country is determined by the longitude of its location on the Earth. A time zone is a region that has the same standard time, and time zones are typically defined as an offset from the Coordinated Universal Time (UTC). In this case, the country has a standard time of GMT + 1 hour, which means it is one hour ahead of the UTC. The longitude that corresponds to this time zone is the one located 15° east of the Prime Meridian, which runs from the North Pole to the South Pole and passes through the Royal Observatory in Greenwich, London, England. So, the local time adopted by the country is 15°E.