Why was the south vulnerable to a blockade by the north?

According to nationalists, a nation-states government should be a. controlled by european monarchs b. led by an appointment president c. voted on by european parliaments d. chosen by that nation-state

Don’t mind the already marked answer but taking it now

What is the tallest mountain range in south america? a guiana highlands b the patagonia mountians c the andes mountians d brazilian mountains