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. 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. A team of scientists that includes Boston University experts has discovered they also produce oxygen on the seafloor. The research team used deep-sea chambers that land on the seafloor and enclose the seawater, sediment, polymetallic nodules, and living organisms. 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. The deep-sea rocks, called polymetallic nodules, don't only host a surprising number of sea critters.

CAT 2025 Slot 3 · VARC · Question 10

CAT 2025 Slot 3 previous year question on Odd One Out, with the answer and a step-by-step solution.

Odd One OutVerbal AbilityType in the answer (TITA)Hard

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.

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.
A team of scientists that includes Boston University experts has discovered they also produce oxygen on the seafloor.
The research team used deep-sea chambers that land on the seafloor and enclose the seawater, sediment, polymetallic nodules, and living organisms.
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.
The deep-sea rocks, called polymetallic nodules, don't only host a surprising number of sea critters.

Answer & solution

Answer: 3

The pronoun in sentence 2 is the key. 'They also produce oxygen on the seafloor' needs an antecedent, and only sentence 5 supplies one – the polymetallic nodules. Notice too that 5 and 2 form a 'not only... also' pair: the nodules don't only host sea critters, they also produce oxygen. So 5 is followed by 2.

Sentence 4 then reacts to that finding – the discovery is a surprise, since oxygen is normally made by plants and organisms with the sun's help, not by rocks on the ocean floor.

Sentence 1 supplies the contrast 4 has just invoked, naming the ordinary case: about half our oxygen is made near the ocean surface by photosynthesising phytoplankton. The paragraph runs 5 – 2 – 4 – 1, a coherent account of a surprising discovery set against the familiar picture.

Sentence 3 describes the method – deep-sea chambers enclosing seawater, sediment, nodules and organisms. Methodology is a different concern from the finding and its significance, and no other sentence picks it up.

Shortcut: with two plausible outliers, keep the one the chain actually needs. Sentence 1 is needed, because 4's contrast between sun-powered organisms and rocks is left hanging without it. Sentence 3 is needed by nothing.

Hence, the answer is 3.

CAT 2025 Slot 3 · VARC · Question 10

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