Question

Difficulty: Very hardSelecting Concluding Sentences and Transitions

Passage:

For centuries, the periodic emergences of Magicicada species—commonly known as periodical cicadas—have fascinated and bewildered biologists. Emerging from their subterranean habitats in massive swarms only once every 13 or 17 years, these insects overwhelm predators through sheer volume. In mathematical biology, researchers have long hypothesized that the prime-numbered lengths of these cycles prevent synchronization with the shorter, cyclical life stages of avian predators. By emerging at prime intervals, the cicadas minimize the frequency of overlapping years with predators whose populations fluctuate on 2-, 3-, or 4-year cycles.

To test this evolutionary hypothesis, computer models have simulated interactions between cicadas and hypothetical predators over tens of thousands of evolutionary generations. The simulations consistently demonstrate that cicada populations with non-prime cycles are rapidly driven to extinction by predators that adapt to their predictable cycles, whereas those with prime cycles survive. This computational evidence supports the theory that numerical primes act as an evolutionary shield, ensuring the cicadas' long-term survival.

Given that all the choices are true, which choice provides the most effective concluding sentence for the paragraph and the passage?

  1. This computational evidence supports the theory that numerical primes act as an evolutionary shield, ensuring the cicadas' long-term survival.Answer
  2. B
    Nevertheless, the research indicates that periodical cicadas may face new threats from climate change as warming subterranean temperatures alter their emergence schedules.
  3. C
    Instead, these models confirm the protective nature of prime cycles, they show that mathematical patterns are deeply embedded in natural history.
  4. D
    On the other hand, the simulations verify that cicadas, that emerge at prime-numbered intervals, are far more likely to avoid predator synchronization.

Answer

The correct option is 'NO CHANGE' because it summarizes the findings of the computer models and connects them back to the evolutionary survival advantages of prime-numbered emergence cycles without introducing new, unsupported topics.
The correct answer (currently 'NO CHANGE') is the most effective because it directly connects the computer simulations ('computational evidence') mentioned in the second paragraph with the evolutionary prime-number hypothesis ('numerical primes act as an evolutionary shield') introduced in the first paragraph, providing a logical and complete conclusion to the entire passage.

Step-by-Step Solution

1
Analyze the passage and identify the main goal of the concluding sentence.
The goal is to summarize the computer simulations from the second paragraph and tie them back to the evolutionary survival theory (prime-numbered cycles preventing predator synchronization) from the first paragraph.
Understanding the rhetorical goal ensures that the selected conclusion fits the passage's overall purpose and themes.
2
Evaluate the grammar and transitions of the options.
Identify that the option beginning with 'Instead' contains a comma splice and an incorrect contrast transition. Identify that the option beginning with 'On the other hand' contains an incorrect contrast transition and misplaced commas around a restrictive clause.
Eliminating options with grammatical errors and incorrect logical transitions narrows down the choices.
3
Evaluate the remaining choices for content relevance.
The option beginning with 'Nevertheless' introduces unsupported details about climate change. The option 'NO CHANGE' provides a grammatically correct summary that links the computational evidence to the evolutionary theory.
The correct conclusion must remain focused on the passage's established scope and cannot introduce new arguments or unsupported details.

Key Concept

Selecting Concluding Sentences and Transitions
Estimated Time:1m 30s
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