Read the passage and answer the questions given below it.
In the summer of 1998, divers in the Lakshadweep lagoons surfaced with a strange report. The reefs had gone white. Branching corals that should have been brown and green stood pale as chalk under warm, clear water. The word for this is bleaching, and it misleads. It suggests something scrubbed clean and finished with. A bleached coral, for a while at least, is still alive.
A coral is a colony of tiny animals called polyps, and it does not live alone. Inside its tissue live even tinier algae. They make food from sunlight, pass most of it on to the coral and give it its colour. When the sea stays too hot for too long, the coral throws the algae out. What is left is clear tissue over a white skeleton. The coral has not died. It has started to starve.
If the water cools in time, the algae can return, and the colour with them. Even a reef that loses much of its coral can grow back, given enough quiet years. Many Lakshadweep reefs did so in the years after 1998. That mattered on land too, because the reef breaks the ocean swell before it reaches the houses on these coral islands.
The trouble lies in the gap between one hot spell and the next. The reefs bleached again in 2010, and again in the marine heatwaves of recent summers. To a reef that needs years to heal, heat that once came as a rare visitor can begin to seem almost unremitting. A coral still weak from the last bleaching meets the next one with less to spare. Where corals die, seaweed spreads over the bare rock, and young corals struggle to settle there.
According to the passage, the algae that live inside a coral
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → hand over to the coral most of the food they make and also give it its colour
The second paragraph says what the algae do for the coral.
- The algae “make food from sunlight” and “pass most of it on to the coral”. So most of the food they make goes to the coral.
- They also “give it its colour”. That is why a coral turns white once the algae are gone.
Why the Other Options are Incorrect?
Option 1: shield the coral from water that has grown too warm for it — Incorrect. Not mentioned: The passage never says the algae protect the coral from heat. In hot water the coral loses them.
Option 2: leave the coral of their own accord once the sea turns too hot — Incorrect. Misread: The algae do not go by choice. The passage says “the coral throws the algae out”.
Option 4: live on food taken from the coral and slowly turn it pale — Incorrect. Contradicted: The food goes the other way. The algae feed the coral, and the coral turns pale only when they leave.