Practice Test: Reading Comprehension - 22 | 100 RCs for GMAT PDF Download

This answer choice accurately describes the main idea of the passage. Note that this idea permeates the entire passage and conveys the main intention of the author. Also, note that this theme is mimicked in the opening paragraph of the passage: “… recent evidence suggests that insects, rather than mammals, may be used more effectively in this capacity.”

The whole passage provides an argument for the increased use of insects’ detection mechanisms. For example, in the second sentence of the first paragraph, the author states that “… insects, rather than mammals, may be used more effectively in this capacity.” Also, the author concludes the passage by saying that “… the detection mechanisms of insects are likely to be applied in practice in the near future.” These statements and the overall tone of the passage suggest that the author is generally optimistic about the use of the detection mechanisms of insects.

The second sentence of the concluding paragraph states that the technique developed by Dietrich Schneider in the 1950s “became the first method that enabled researchers to record the activity in insect olfactory nerves and identify the compounds that trigger a behavioral response.” Since this technique became the first method, we can infer that no reliable methods had existed prior to the development of this technique, i.e. in the first half of the twentieth century or earlier.

The first paragraph discusses the disadvantages of using dogs in detecting drugs and states that “… problems may also result from the emotional relationship between a dog and its owner.” Therefore, it can be inferred that if dogs could not develop emotional relationships with humans, this problem would be addressed, thus rendering their use more effective.

The third sentence in the second paragraph states that “This protein carries the hydrophobic ligand through the lymph fluid found inside the cell and attaches it to a receptor on the dendritic projections of a sensory nerve cell.”