GRE Reading Comprehension: ETS Official Practice 150-GRE OP150: 阅读 - 934A737N74NL60NWZ

It can be inferred that the author of the passage would agree with which of the following about the origin of UHECRs that reach Earth? A. The origin is something other than supernovas in the Milky Way. B. The origin is most likely something other than very distant quasars or gamma-ray bursts. C. The origin is most likely no more than a little over 100 million lightyears away from Earth.