QUESTION TEXT: Bird watcher: The decrease in the mourning…
QUESTION TYPE: Strengthen
CONCLUSION: There are fewer mourning doves because there is less nesting habitat for them in the area.
REASONING: Mourning doves used to nest in orchards until sprinklers were installed.
ANALYSIS: This argument makes a causation-correlation error. True, the mourning dove decline happened at the same time that the sprinklers were installed. But that doesn’t mean that the habitat decline caused the decrease of doves in the area. There could have been other, more important reasons: less food, more predators, new food supply in a different area, etc.
The argument has also failed to show that the loss of the orchard truly was a problem for the mourning doves. If there was still much available habitat in the area, then loss of the orchard likely wasn’t the cause. Answer B addresses this by showing that the orchard was the only suitable habitat.
You might have thought “maybe the sprinklers didn’t truly ruin the orchard as habitat”. This is possible, but unlikely – sprinklers are pretty disruptive. Answer C does address this possibility by showing that the sprinklers were indeed a problem. If B didn’t exist, I would have chosen C. But B is a far stronger answer. It’s rare for there to be two answers that strengthen an argument, but this question shows that it’s possible. In such cases, you should follow the question stem’s direction: you’re choosing the answer that most strengthens the argument.
- This weakens the argument by providing an alternate cause. If mourning doves can now be hunted, then maybe hunting is the cause of the decline.
- CORRECT. This strengthens the argument by increasing the impact of the sprinklers. The sprinklers affected the doves’ only habitat.
- I think this answer does slightly strengthen the argument, by confirming that the sprinklers ruined the orchard as a habitat. But it’s not much of a strengthen. It’s already pretty reasonable to assume that sprinklers ruin trees as a habitat. Further, this doesn’t show that the doves actually lacked habitat in the area. If other trees were suitable, then loss of the orchard wouldn’t have been a big deal. Only B shows that the orchard was a critical habitat.
- This doesn’t have any impact. Only a change would have reduced the number of morning doves. This answer doesn’t say that residents changed what they put in their feeders.
- This is too vague to be useful. We already knew that the doves nested in apple trees. This just tells us doves often nest in fruit trees. But it doesn’t mean that only apple trees make good habitats for doves. This actually weakens the argument slightly by showing that other fruit trees in the area might have made good replacement habitats.
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