What does the author imply by saying "Not a single pebble was found that might have indicated that the pebbles came from the nearby continent"? A. The most obvious explanation for the origin of the pebbles was not supported by the evidence. B. The geologists did not find as many pebbles as they expected. C. The geologists were looking for a particular kind of pebble. D. The different pebbles could not have come from only one source.