Complete Question Explanation
A Parallel Reasoning question that is perhaps best approached with a combination of focus on the conclusion ("It's good that this happened") and an abstraction of the stimulus (something like "This made us look at X, and even though X turns out not to be the real problem here, it's good that we are looking at X anyway.") We must find an answer that has that same abstract structure, including the same type and strength of conclusion ("this is good").
Answer A: In this answer we see that there is nothing looked at that has been determined not to be the real problem - there's no "X" to match our abstraction. The conclusion also fails to match, as it says "it's good that this isn't all we are looking at." Loser.
Answer B: This is the correct answer. Here, our "X" is oversight, and our conclusion is that, while oversight wasn't the actual problem in this case, it's good that we are looking at it anyway. A perfect match for our abstraction and conclusion!
Answer C: As with answer A, nothing has been eliminated as a problem - there is no "X". Also, our conclusion is not about he good that comes from looking at X, but instead is about the good that may come from the problem itself occurring.
Answer D: The conclusion here is jarringly different from what we wanted to see, telling us about the harm of looking at X rather than the good that can come from doing so. As such, this answer must be rejected.
Answer E: In this answer, "X" (corruption in this case) is in fact the real, main problem. In our abstraction, we rejected X as the problem but were nonetheless happy to be looking at it for its own sake. As this fails to follow our abstraction of the stimulus, it is a loser.