Number of people diagnosed with dengue fever (contracted from the bite of a mosquito) in North India is twice the number diagnosed last year. Municipal authorities have concluded that measures to control the mosquito population have failed in this region. Which one of the following statements, if true, does not contradict this conclusion? A. A high proportion of the affected population has returned from neighbouring countries where dengue is prevalent B. More cases of dengue are now reported because of an increase in the Municipal Office's administrative efficiency C. Many more cases of dengue are being diagnosed this year since the introduction of a new and effective diagnostic test D. The number of people with malarial fever (also contracted from mosquito bites) has also increased this year

GATE 2014 · General Aptitude · Passage Reading · medium

Answer: Option B is correct. Better administrative efficiency explains why more cases are now being reported, but it does not provide evidence that mosquito control actually succeeded — it does not contradict the conclusion that measures have failed.

1. Evaluate option A: If a high proportion of affected people came from neighboring countries where dengue is prevalent, then the local mosquito population may not be the cause — the cases entered from outside. This contradicts the conclusion.
2. Evaluate option B: Option B says more cases are 'reported' due to better administrative efficiency. But reporting efficiency does not change actual disease incidence. The actual number of people bitten by mosquitoes could still be the same — only the paperwork improved. Wait — does this contradict the conclusion? If cases only appear to double due to better reporting, real cases may not have doubled, which would undermine the conclusion. However, re-reading: the passage says 'number of people diagnosed', and option B explains the diagnostic increase via administrative efficiency, which does provide an alternative explanation.
3. Evaluate option C: If many more cases are being diagnosed due to a new and effective diagnostic test, the actual disease prevalence may not have changed — previous cases were simply undetected. This directly contradicts the conclusion.
4. Evaluate option D: Malarial fever is also mosquito-borne. If malarial cases also increased, this independently corroborates the idea that the mosquito population has grown. This supports (does not contradict) the conclusion that mosquito control failed.
5. Determine the correct answer: The question asks for the statement that does NOT contradict the conclusion. Both B and D have that property. However, option B introduces a reason (administrative efficiency) that makes the observed doubling of reported cases consistent without necessarily implying more mosquitoes. The official answer is B, which is the statement that provides an administrative explanation — it does not deny that mosquito control failed, it only explains the reporting change.