单选题 .  ①Climatologists observed in 1964 that a slow warming of the surface of the North Atlantic in the 1910s and 1920s could well have been driven by a surge of warm water up the Gulf Stream. ②This Atlantic warming accompanied a global warming that by the 1940s had produced the highest global temperatures to that point in the records. ③It was so warm that statistical techniques used in the 1990s to detect the "fingerprint" of greenhouse warming in climate records also show the 1940s having greenhouse warming. ④However, no one believes enough greenhouse gases had reached the atmosphere by then to cause much of a human-induced warming. ⑤That inconsistency has led greenhouse contrarians to claim that any recent warming could be natural rather than anthropogenic.19.  It can be inferred that the "contrarians" mentioned in the passage would agree with which of the statements? ______