Some claim that migratory birds have an innate homing sense that allows them to return to the same areas year after year. However, there is little evidence to support this belief, since the studies testing whether the accuracy of birds' migratory patterns is due to such an innate ability are inconclusive. After all, birds may simply navigate using landmarks, just as humans do, and we do not say that humans have an innate sense of direction simply because they find their way home time after time. Which one of the following statements most accurately expresses the main conclusion drawn in the argument? ["The ability to use landmarks to find one's way home is probably not an innate ability in birds.", "Studies testing whether the accuracy of birds' migratory patterns is due to an innate homing sense are inconclusive.", 'There is as yet little reason to accept that birds have an innate homing sense.', 'It is as false to claim that humans have an innate sense of direction as it is to claim that birds have an innate homing sense.']