Answer: A. North Vietnam took over South Vietnam when the US troops left
Explanation: Communist forces ended the war by seizing control of South Vietnam in 1975, and the country was unified as the Socialist Republic of Vietnam the following year.
Justinian I served as emperor of the Byzantine Empire from 527 to 565. Justinian is best remembered for his work as a legislator and codifier. During his reign, Justinian reorganized the government of the Byzantine Empire and enacted several reforms to increase accountability and reduce corruption.
Because of increasing sea ice.
In climate change taking place since then, there has been an opposite problem. Beginning in the late 19th century, a reduction of sea ice has been progressing in the Arctic regions. The pace of ice mass loss has been accelerating especially since the 1970s. In the first decade of the 21st century, Greenland's ice loss accelerated at a rate of 30 gigatonnes a year.