A local chemical plant produces pesticides that can cause sterility in small mammals such as otters.
Conclusion (Therefore)
Pesticides are definitely contaminating the river.
Evidence
A local plant makes pesticides that can cause sterility in small mammals such as otters. Soon after the plant began operating, the incidence of sterility among the otters in a nearby river increased dramatically.
Evaluate
The author is trying to Explain a Curious Fact: Why did the incidence of sterility among local otters go up so much?
She takes one possible explanation: Maybe it's because of that new plant that started operating; they produce pesticides that can cause sterility in otters
and overconfidently concludes that this is the explanation: The pesticides are definitely contaminating the river
Goal
To match this famous Causal flaw, we would want at a minimum a) A curious fact b) A conclusion in which the author overconfidently is sure of one possible explanation for that fact
To match it more closely, the curious fact should be a chronological association:
The supposed effect started happening soon after the supposed cause started happening