Mystery stories often feature a brilliant detective and the detective’s dull companion.
Information
Mysteries often have a smart detective and dumb sidekick.
As clues are introduced, the dumb sidekick arrives at incorrect conclusions, whereas the smart detective uses those same clues to arrive at the correct solution.
For the author, having the dumb sidekick in the story is way to give readers a chance to solve the mystery (like the smart detective), as well as a way to throw them off the scent (since the dumb sidekick puts incorrect suggestions in the reader's mind).
Evaluate
We're looking for hidden truths we can pull out. Two or more claims with overlapping information that we can combine.
The dull companion is brought up in all three sentences. The Thus at the beginning of the last sentence seems to show a causal connection between the 2nd and 3rd sentence.
And there's a Comparison (difference) in the 2nd sentence: companion looks at the clues, wrong solution detective looks at same clues, right solution
Maybe since the last sentence is saying that the story gives the reader enough info to solve the mystery, the answer is going to be combining these ideas to say something like, .
Goal
With no clear clues, we should just head to the answers and try to find a safely worded claim that is derived by combining 2 or more ideas.