Q. Consider the following pairs:

1. Guyot – Flat-topped submerged seamount
2. Thermocline – Rapid salinity change with depth
3. Upwelling – Rising of nutrient-rich deep water
4. Abyssal Ridge – Deep flat ocean floor

Which of the above pairs is / are correctly matched?
Answer: 1 and 3 only
Notes: Pair 1 is correct: Guyot refers to a flat-topped submerged seamount. Pair 2 is incorrect as a thermocline is characterized by a rapid temperature, not salinity, change with depth. Pair 3 is correct: upwelling brings nutrient-rich waters to the surface. Pair 4 is incorrect; "Abyssal Ridge" is not a deep flat ocean floor, which is actually an abyssal plain.