CAT 2025 Slot 3 VARC Question & Solution
Question
Five jumbled sentences (labelled 1, 2, 3, 4, and 5), related to a topic, are given below. Four of them can be put together to form a coherent paragraph. Identify the odd sentence out and key in the number of that sentence as your answer.
1. About half of all the oxygen we breathe is made near the surface of the ocean by phytoplankton that photosynthesize just like land-dwelling plants.
2. A team of scientists that includes Boston University experts has discovered they also produce oxygen on the seafloor.
3. The research team used deep-sea chambers that land on the seafloor and enclose the seawater, sediment, polymetallic nodules, and living organisms.
4. The discovery is a surprise considering oxygen is typically created by plants and organisms with help from the sun—not by rocks on the ocean floor.
5. The deep-sea rocks, called polymetallic nodules, don’t only host a surprising number of sea critters.
Solution
Main Idea of the Paragraph
The sentences discuss a new scientific discovery: oxygen is being produced on the ocean floor, which challenges the long-held belief that oxygen production requires sunlight and photosynthesis.
The focus is on moving from an accepted scientific understanding to a surprising new finding that reshapes how oxygen production is understood.
Explanation of the Correct Sequence
Why Sentences 1 → 2 → 4 → 5 Fit Together
-
Sentence 1 works as the opening because it explains the commonly accepted view:
- Oxygen is produced by phytoplankton near the ocean surface
- This establishes the traditional understanding linked to sunlight
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Sentence 2 follows naturally by introducing the new discovery:
- Oxygen is also being produced on the seafloor
-
Sentence 4 then highlights why this finding is surprising.
- Oxygen production is usually associated with sunlight
- This contrast reinforces how unexpected the discovery is
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Sentence 5 adds supporting detail.
- It explains the role of polymetallic nodules
- This connects deep-sea rocks to the unexpected oxygen production
Together, these sentences move logically from established knowledge → new finding → explanation of surprise → scientific detail.
Why Sentence 3 Is the Odd One Out
- Sentence 3 focuses on how the research was conducted
- It shifts attention from:
- What was discovered
- Why the discovery matters
Since the other sentences focus on the idea and implications of oxygen production, sentence 3 disrupts the flow.