Read the passage and answer the questions given below it.
When a field gives a good crop, the farmer, the rain and the seed usually share the credit. Hardly anyone thinks of the earthworm. It lives out of sight, it is slimy, and most people meet it only on a wet path after a storm. Yet much of the work that keeps soil alive goes on in its dark tunnels.
An earthworm eats its way through the ground, swallowing soil along with bits of dead leaves and roots. What comes out at the other end, called a cast, is richer in plant food than the soil around it. Its burrows matter just as much. They let air reach the roots, and they help rainwater soak in instead of running off the surface.
Charles Darwin watched these animals on and off for about forty years. His last book, published in 1881, was about earthworms. He estimated how fast their casts piled up, and he showed that stones and even old ruins left on the ground slowly sink under it, buried a little at a time by the soil the worms bring up.
Today many gardeners keep worms to turn kitchen waste into vermicompost. On farms, though, the story often runs the other way. Repeated deep ploughing tears up their burrows, and some pesticides kill them or bring their numbers down. The loss does not show at once. It shows later, in soil that packs hard and lets water stand on top after rain.
The main purpose of the passage is to:
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → show how a little-noticed animal keeps soil healthy and how farming can harm it
The passage first shows the useful work of an animal people hardly notice, and then shows how farming can harm it.
- It opens with the point that “hardly anyone thinks of the earthworm”, even though the soil depends on it.
- It then explains the work: casts rich in plant food, and burrows that let in air and rainwater. Darwin’s study shows how much soil the worms move.
- The last paragraph turns to farms, where deep ploughing and some pesticides bring worm numbers down and the soil suffers.
Why the Other Options are Incorrect?
Option 2: urge farmers to plough less deeply and to make their own vermicompost — Incorrect. Not mentioned: The passage says that deep ploughing harms worms and that gardeners make vermicompost. It never tells farmers what to do.
Option 3: describe how Darwin studied earthworms and what his last book set out to prove — Incorrect. Too narrow: Darwin fills only the third paragraph. He is there as support for the main point about the worm’s work.
Option 4: compare how much the farmer, the rain and the seed each add to a good crop — Incorrect. Wrong focus: The farmer, the rain and the seed are named only in the first line, to show who usually gets the praise. The passage never compares them.