Self-study
An unstable climate was probably a major cause of the fall of the Roman empire. Tree-ring analysis shows that Europe's climate underwent extreme fluctuations between 250 A.D. and 550 A.D., a period that encompasses Rome’s decline and fall. This highly variable climate surely hurt food production, which made the empire harder to rule and defend.
2.
Which one of the following, if true, most strengthens the argument?
a
Political failures within the Roman empire during its last years led to conflicts that hampered agricultural production.
This weakens the author’s hypothesis by providing an alternative explanation for the fall of the Roman empire. Either way, this doesn’t support unstable climate as a major cause.
Directionally wrong
Directionally wrong
Answers that, if they have any effect, do the opposite of what we want (weaken when we're trying to strengthen, or strengthen when we're trying to weaken).
b
The areas of the Roman empire that had the greatest climatic instability between 250 A.D. and 550 A.D. did not experience unusual levels of unrest during that period.
This weakens the author’s assumption that an unstable climate had a negative enough effect to bring down the empire; if that were the case, we would expect the areas with more climactic instability to have higher unrest.
Directionally wrong
Directionally wrong
Answers that, if they have any effect, do the opposite of what we want (weaken when we're trying to strengthen, or strengthen when we're trying to weaken).
c
Poor farming practices led to depleted soil in many parts of Europe during the last years of the Roman empire.
This weakens the author’s hypothesis by providing an alternative explanation for instability due to poor food production: poor farming practices, rather than an unstable climate. In other words, the unstable climate may have only been a minor cause.
Directionally wrong
Directionally wrong
Answers that, if they have any effect, do the opposite of what we want (weaken when we're trying to strengthen, or strengthen when we're trying to weaken).
d
During periods when the Roman empire was thriving, Europe consistently experienced weather that was favorable for agriculture.
This strengthens the author’s hypothesis by more closely correlating climate stability with the empire’s strength, supporting the hypothesis that an unstable climate could have been a major factor in the empire’s failure.
Plausibility
Plausibility
Presenting evidence that corroborates (in Strengthen) or conflicts (in Weaken) with the author's hypothesized explanation or the predictions that follow from that explanation.
e
Total food production in Europe was likely greater in the years around 550 A.D. than in the years around 250 A.D.
This is irrelevant, because it still doesn’t tell us how significant the impact of the unstable climate was on food production. Sure, production rose and fell, but how much? It also doesn’t offer any explanation of how food production impacted the Roman empire.