[|] Answer [|]
> The Earthquake's strength
[|] Explanation [|]
The Earthquakes' Strength - Incorrect
This is implying that there is more than one Earthquake. If there was, then the word "Strength" would be changed.
The Earthquakes's Strength - Incorrect
This is grammatically incorrect. You never have two "s".
The Earthquake's Strength - Correct
This is correct. The ' mark in the sentence makes us realize that the strength belong to that earthquake.
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