The statement below is followed by four options. Each option is related to the item in the statement, but only one is always true. Select the option that always holds and makes the statement true.
"A volcano always has ______."
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → An opening in the Earth's crust
The answer must hold for every volcano, without exception. An option that is present in most cases but can be missing in even one case is not always true.
Option (1) Flowing lava — lava flows only during an eruption; a dormant or extinct volcano has no flowing lava.
Option (2) A snow-covered top — Barren Island volcano in the Andaman Sea has no snow.
Option (3) An opening in the Earth's crust — a volcano is a vent (opening) in the Earth's crust through which molten material comes out; without the opening there is no volcano, so this is always true.
Option (4) Smoke coming out all the time — most volcanoes are quiet for long periods and give out no smoke then.