Premise: A survey of a group of people between the ages of 75 and 80 found that those who regularly played the card game bridge tended to have better short-term memory than those who did not play bridge.
Previous conclusion: playing bridge can help older people to retain and develop their memory.
New conclusion/counter-conclusion: it may well be that bridge is simply a more enjoyable game for people who already have good short-term memory and who are thus more inclined to play.
To answer this question, one needs to analyze the two conclusions that were drawn from the premise.
From the premise, the previous conclusion established that playing bridge can help older people to retain and develop their memory. Basically, the first conclusion is establishing a cause and effect relationship between playing bridge and the ability of older people to develop and retain memory. The first conclusion established
the cause as:
playing bridge and
the effect as:
the ability of older people to develop and retain memory.The second conclusion, on the other hand, reverses the cause and effect relationship in the first conclusion by stating that
it may well be that bridge is simply a more enjoyable game for people who already have good short-term memory and who are thus more inclined to play.The second conclusion established
the cause as:
older people with good short-term memory and
the effect as:
more inclined to play bridge.
Based on the above, we can clearly see that the author provides an alternative hypothesis to explain the data on which the first conclusion was drawn.
(A) challenging the representativeness of the sample surveyed
Incorrect. The author did not challenge the representativeness of the sample surveyed, he merely established an alternative hypothesis based on the given information in the premise.
(B) conceding the suggested relationship between playing bridge and short-term memory, but questioning whether any conclusion about appropriate therapy can be drawn.
Incorrect. The author did not concede to any relationship already established between playing bridge and short-term memory. Instead, he reversed the causality relationship established in the first conclusion.
(C) arguing that the original conclusion relied on an inaccurate understanding of the motives that the people surveyed have for playing bridge
Incorrect. The author did reverse the causal relationship in the first conclusion, but the author did not say that the original conclusion relied upon an inaccurate understanding of the motives of the people playing bridge.
(D) providing an alternative hypothesis to explain the data on which the original conclusion was based.
This is the right answer and this is in line with the reasoning provided above.
(E) describing a flaw in the reasoning on which the original conclusion was based
Incorrect. The author did not describe a flaw in the argumentation. All that the author did was that the author established an alternative hypothesis to the hypothesis arrived at in the previous conclusion.