According to the passage, the astronomers rejected gravitational lensing as an explanation for their findings because A. gravitational lensing can cause supernovas to appear brighter than they really are B. their calculations showed a negligible effect of gravitational lensing for light rays from distant sources. C. light rays traveling from the supernovas studied did not have to skirt galaxies. D. the effect of gravitational lensing on the appearance of supernovas is unpredictable. E. the supernovas studied were too near for gravitational lensing to have the observed dimming effect.