Early in this century Alfred Wegener developed the concept of continental drift. His ideas were rejected vehemently because he postulated no identifiable force strong enough to make the continents move. We have come to accept Wegener' s theory, not because we have pinpointed such a force, but because new instruments have finally allowed continental movement to be confirmed by observation. The passage best illustrates which one of the following statements about science? ['Science, employing statistics and the laws of probability, is concerned not with the single event but with mass behavior.', 'In accepting a mathematical description of nature, science has become far more accurate at identifying underlying forces.', 'The aim of science is to define the manifold of nature within the terms of a single harmonious theory.', 'When the events a theory postulates are detected, the theory is accepted even without an explanation of how those events are brought about.']