The graph above shows population of Brazil's largest cities according to the graph how does Brazil's third largest city compare with its second largest city

B. the third-largest city is about one half the size of the second-largest city.

The second largest city in Brazil is Rio de Janeiro, while the third biggest is the capital Brasilia. Rio de Janeiro has an estimated population of around 6,5 million people while Brasilia has little less than 3 million. This makes Rio de Janeiro more than twice bigger in population than the capital of Brazil, Brasilia. But there's something interesting in here in the background, in the past 6 years the population of the second Rio de Janeiro has only increased by little over 9%, while Brasilia's population has increased by around 20% which is more than twice in increase, so if that trend continues in the coming few decades Brasilia will come on top of Rio de Janeiro very quickly.