Identify the continent from the given features A and B: A. It is the smallest…

Continents are distinguished using measurable geographic criteria: their total land area (which ranks the seven continents from smallest to largest), their position relative to the equator (whether a continent lies wholly within one hemisphere or straddles both), and whether the landmass is completely encircled by ocean with no land connection to any other continent — the basis for the informal label ‘island continent’.

Applying clue A — the smallest continent lying entirely in the Southern Hemisphere — Australia fits: at roughly 7.7 million km² it is the smallest of the seven continents, and its entire landmass, including Tasmania, lies south of the equator. Clue B — the ‘island continent’ — is the traditional epithet for Australia because it is completely surrounded by the Indian and Pacific Oceans with no land bridge to Asia or any other continent.

The other options each fail one or both clues:

• Antarctica also lies entirely in the Southern Hemisphere, but at roughly 14.2 million km² it is far larger than Australia, so it fails the ‘smallest continent’ clue; as a permanently ice-covered polar landmass it has never been popularly termed the ‘island continent’ either.

• South America extends from about 12°N to roughly 56°S, so it straddles the equator rather than lying wholly in the Southern Hemisphere, and at about 17.8 million km² it is one of the larger continents — failing both clues.

• Africa also straddles the equator — its northern regions lie in the Northern Hemisphere — and at about 30.4 million km² is the second-largest continent, so it likewise fails both clues.