Task reminder: Read the passage, then select the one correct answer. No negative marking. Read the question first, then skim for the relevant paragraph.

1. Sample Text 1

Aquaculture — the farming of fish, shellfish, and aquatic plants — now supplies more than half of the world’s seafood and is one of the fastest-growing food production sectors globally. As wild fish stocks are depleted by overfishing, aquaculture is widely promoted as a sustainable alternative. However, intensive fish farming generates significant environmental concerns: dense populations of fish in cages produce concentrated waste, consume large quantities of wild-caught fish as feed, and can spread diseases and parasites to wild populations. More sustainable aquaculture models — including integrated multi-trophic systems and the farming of filter feeders such as mussels and oysters — offer potential solutions but remain a small fraction of total production.

Q. What environmental concern about conventional aquaculture is described in the passage?

A. It requires the genetic modification of fish to achieve commercial yields.
B. It produces dense fish populations that generate waste and risk disease spread.
C. It uses entirely synthetic feeds that harm marine ecosystems.
D. It has been shown to reduce wild fish populations through competition.

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2. Sample Text 2

The concept of “rewilding” involves restoring ecosystems to a more natural state by reintroducing keystone species and removing human management where possible. The reintroduction of wolves to Yellowstone National Park in 1995 is often cited as a transformative example: the presence of wolves altered elk behaviour, reducing overgrazing in river valleys, which led to vegetation recovery, reduced river erosion, and increased biodiversity in a cascade of ecological effects known as a “trophic cascade.” Critics of rewilding argue that it is impractical in densely populated regions and can create conflicts between wildlife and farming communities.

Q. What effect did reintroducing wolves to Yellowstone produce, according to the passage?

A. It directly eliminated overgrazing by reducing elk populations dramatically.
B. It triggered a series of cascading ecological changes that improved the ecosystem.
C. It caused conflict with nearby farming communities and was later reversed.
D. It increased river erosion by disrupting natural sediment flows.

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3. Sample Text 3

The field of astrobiology — the study of the potential for life elsewhere in the universe — has been energised by recent discoveries. The detection of organic molecules on Mars, water ice in permanently shadowed lunar craters, and subsurface liquid water oceans on Jupiter’s moon Europa and Saturn’s moon Enceladus have expanded the range of environments considered potentially habitable. Extremophile research on Earth — studying organisms that thrive in conditions of extreme heat, cold, acidity, or radiation — provides analogues for how life might survive in similarly harsh extraterrestrial settings. Despite this growing body of evidence, no confirmed detection of extraterrestrial life has yet been made.

Q. What is the significance of extremophile research for astrobiology?

A. It has confirmed the presence of microbial life in the subsurface oceans of Europa.
B. It provides models for how life might survive in harsh extraterrestrial environments.
C. It has shown that organic molecules can form in outer space.
D. It demonstrates that Mars once had conditions suitable for complex life.

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