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.
"An ocean always has ______."
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → Salt water
The answer must hold for every ocean, without exception. An option that is present in most cases but can be missing in even one case is not always true.
Option (1) Coral reefs — corals grow only in warm, shallow, clear water; the cold Arctic Ocean has no coral reefs.
Option (2) Icebergs floating on it — icebergs are found only in cold polar waters, not in warm tropical seas.
Option (3) A frozen surface — only the cold polar waters freeze; warm tropical seas never have a frozen surface.
Option (4) Salt water — the water of every ocean is salty because of the salts dissolved in it, so this is always true.