The oceanic trenches or the narrow depressions on the seafloor are formed by reason of:
Show answer & explanation
Correct answer: C
Explanation
The Correct Answer is option 3 i.e. tectonic activity .
Oceanic trenches or narrow depressions on the seafloor are formed primarily due to tectonic activity, specifically where one tectonic plate is forced beneath another in a process called subduction. This creates deep, narrow trenches such as the Mariana Trench.
Other options :
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Tidal currents: Movement of water caused by tides, not responsible for trenches.
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Tsunamis: Large sea waves caused by underwater earthquakes or landslides, but don’t form trenches.
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Thermohaline circulation: Ocean circulation driven by temperature and salinity differences, unrelated to trench formation.