I have a doubt between options B and C - I liked both of them but chose the wrong one (B). Can anyone explain why B is wrong? I do think it shows that the position “It would seem sensible…BILLIONS OF LIGHT YEARS…” is self-contradictory given the evidence of the last line, which states that it cannot be more than 100 million light years
The plausible position (quasars being the source) is not self-contradictory, i.e., you require another ‘outside’ fact (which is not in the theory itself), of UHECRs colliding with photons to contradict it.