"Surprising" Phenomenon
Why did indigenous Australians and indigenous Tasmanians develop such different cultures and technologies within 2,000 years of being separated?
Objective
The correct answer must fail to explain why indigenous Australians developed technologies that indigenous Tasmanians did not. Every wrong answer, meanwhile, will offer a difference between the groups explaining why their cultures and technologies diverged.
A
After the disappearance of the land bridge the indigenous Tasmanians simply abandoned certain practices and technologies that they had originally shared with their Australian relatives.
This is a difference between the groups that explains the technological discrepancy. Both cultures were positioned to make the developments in question, but the indigenous Tasmanians gave up some tools and practices.
B
Devices such as the spear-thrower and the boomerang were developed by the indigenous Tasmanians more than 10,000 years ago.
This deepens the mystery. Indigenous Tasmanians invented these technologies, yet they were absent from Tasmanian society 2,000 years later.
C
Technological innovations such as fishing nets, polished stone tools, and so on, were imported to Australia by Polynesian explorers more recently than 10,000 years ago.
This explains the technological discrepancy. Polynesian explorers are responsible, because they introduced technologies to indigenous Australians but not to indigenous Tasmanians.
D
Indigenous people of Australia developed hunting implements like the boomerang and the spear-thrower after the disappearance of the land bridge.
This contributes to an explanation of the technological discrepancy. Indigenous Australians developed these tools after the land bridge disappeared, so they were not introduced to indigenous Tasmanians.
E
Although the technological and cultural innovations were developed in Australia more than 10,000 years ago, they were developed by groups in northern Australia with whom the indigenous Tasmanians had no contact prior to the disappearance of the land bridge.
This contributes to an explanation of the technological discrepancy. Indigenous Tasmanians were not introduced to the developers of these technologies before the land bridge disappeared.
"Surprising" Phenomenon
Why did people who received the hepatitis A vaccine exhibit symptoms of hepatitis A?
Objective
A hypothesis resolving this discrepancy must reveal new information about the group who received the vaccine. It should either indicate their infection with hepatitis A prior to inoculation or distinguish between the hepatitis A virus and the symptoms it causes.
A
The placebo did not produce any side effects that resembled any of the symptoms of hepatitis A.
This does not imply that the vaccine did produce such side effects. It refers to placebo recipients only, and does not address the discrepancy, which involves only vaccine recipients.
B
More members of the group that had received the placebo recognized their symptoms as symptoms of hepatitis A than did members of the group that had received the vaccine.
This is irrelevant information. There is no indication that participants self-reported their symptoms, so this difference in attribution between the groups would not have affected the study.
C
The people who received the placebo were in better overall physical condition than were the people who received the vaccine.
This does not explain why people who received the vaccine developed hepatitis A symptoms. The discrepancy is not between the two groups, but between the vaccine's complete effectiveness and the hepatitis A symptoms among the people who received it.
D
The vaccinated people who exhibited symptoms of hepatitis A were infected with the hepatitis A virus before being vaccinated.
This resolves the apparent paradox by explaining that vaccine recipients were infected prior to inoculation. It is consistent because the author gives no information about the vaccine's effect on patients already infected with hepatitis A.
E
Of the people who developed symptoms of hepatitis A, those who received the vaccine recovered more quickly, on average, than those who did not.
This does not explain how vaccine recipients developed symptoms in the first place. If the vaccine is completely effective, patients who received it should not have contracted hepatitis A.