The correct answer is - B. Lake Nasser was scheduled to flood the valley where the temple was located.
During the 1960's the Lake Nasser experienced an increase at it's water levels and the valley was in constant threat to be flooded by its waters. In close proximity to the lake was also located the Abu Simbal temple which is of great national, cultural, historical meaning for the Egyptians, so the government decided to intervene and save one of the national treasures and not let it be destroyed. So they practically performed a rescue mission of the temple and moved it away from the valley threatened by the Lake Nasser and onto a safer ground.