Passage Summary: An archaeologist argues that deep ruts in Malta weren't dug out by people; they were worn down by carts until they became too deep to use.

Conclusion: The ancient tracks found on Malta were probably formed by the natural erosion of wheels rather than being carved by hand.

Reasoning: While some point to uniform depth as evidence of manual cutting, that uniformity actually results from vehicles abandoning tracks once they erode too deep for the wheels.

Analysis: The archaeologist starts with their main point, then spends the rest of the stimulus debunking a rival theory. The core of the argument is the first sentence. When identifying the conclusion in a 'counter-premise' structure like this, look for the claim that the author is defending against the 'some researchers suggest' crowd. The evidence about wheel diameter is used to explain away the evidence for the opposing view.