Question

According to the passage, before the discovery of new techniques for detecting viral DNA, population ecologists believed that viral diseases ______

• A. Were not widely prevalent among insect populations generally.
• B. Affected only the caterpillar life stage of lepidoptera.
• C. Were the driving force behind lepidoptera population cycles.
• D. Attacked already declining caterpillar populations.
• E. Infected birds and parasites that prey on various species of lepidoptera.

Answer 1

The correct option is D Attacked already declining caterpillar populations.

Option D is the riight answer because it is clearly illustrated in the middle of the passage that - 'For many years, viral disease had been reported in declining populations of caterpillars, but population ecologists had usually considered viral disease to have contributed to the decline once it was underway rather than to have initiated it.'

There is no evidence in the passage to suggest that Options A, B, C, and E are the right answers.

Hence, these are incorrect,