Q18 - Dobson: Some historians claim

[ManhattanPrepLSAT1]

The argument concludes that the people who built the ring of stones were not knowledgeable about celestial events. Why? Well it says that the evidence supporting the view that these people were knowledgeable about celestial events is false.

Okay, so losing your evidence doesn't mean you've lost your argument. Answer choice (A) describes this very issue.

Incorrect Answers
(B) describes the wrong flaw. There's no contradiction here.
(C) doesn't even describe an error of reasoning.
(D) describes the wrong flaw. Nothing in the argument is merely a matter of opinion.
(E) describes the wrong flaw. There's no equivocation of meaning here.

[AddisonB58]

How is D wrong? I don't quite understand how the belief that because the stone's were pointed towards the equinox this means they had knowledge of celestial events is false is not an opinion. Dobson's opinion is that it is not likely the stone's were pointed to the equinox intentionally.