The correct answer is - B. to populate the country's interior.
Unlike the other big and important cities in Brazil that are on the eastern coast or very close to it, the newly promoted and built capital of Brasilia has been deliberately constructed in the interior of the country.
The purpose for this move by the government was to populate and develop the interior of Brazil, so that the country is less centralized, and the people and industry redistributed more evenly thought the country.
Despite the idea being with good intentions, and the city being built nicely, with also the politicians and ordinary people living in the same buildings and being in touch on daily basis, it was unfortunately a disaster.
Most of the people did not wanted to move in the new capital, still preferring the likes of Rio de Janeiro and Sao Paolo, and the city never functioned properly, or developed as wished. After some time, big portion of the people that initially moved in there decided to move away from it.