Historian: The Land Party achieved its only national victory in Banestria in 1935.
Conclusion (I conclude)
The success of the Land Party that year was due to the combination of the Land Party’s specifically addressing the concerns of agricultural and small business interests and the depth of the economic problems people in these groups were facing.
Evidence
The Land Party achieved its only national victory in Banestria in 1935.
It received most of its support that year in rural and semirural areas, where the bulk of Banestria’s population lived at the time.
The economic woes of the years surrounding that election hit agricultural and small business interests the hardest, and the Land Party specifically targeted those groups in 1935.
Evaluate
Since the Land Party's victory in 1935 was it's only national victory, it would qualify as an anomaly / a Curious Fact. And since the conclusion is causal, "X was due to Y and Z", we can definitely use our Explain Curious Fact framework.
Curious Fact: why did the Land Party win in 1935?
Author's Explanation: agricultural and small business interests were really economically struggling in those years, and the Land Party specifically addressed the concerns of those groups.
Goal
The two pressure points are 1. Alternate Explanations for the curious fact 2. the plausibility of the Author's Explanation
We can strengthen by ruling out an alternate explanation for the Land Party’s success or strengthen by making the author's explanation seem more plausible.