What country supported South Vietnam? What was the capital of North Vietnam?Immersive Reader

South Vietnam was supported by the USA.  The Capital: Saigon.

Explanation: South Vietnam was a part of  Western colonial realm, the Northern made part of Communist empire ruled from Moscow. After the WW II there was a new paradigm. What made part of it was 1) decolonization process (human rights put in practice in the so-called Third Word), 2) Cold War. Paradox of that time that those nations who decided to get free from western colonial empires (Angola, Congo, Mosambique, Vietnam) were hurrying to the embrace of Soviet Communist empire (another sort of colonialism). Northern Vietnam became part such an "ally" of USSR and the West had to apply containment doctrine in Southern Vietnam.

what are the options?

d. the polar jet stream   lies between the polar easterlies and trade winds should be your answer