Recent field studies, however, reveal that on dives in the wild, the seal usually heads directly for its prey and returns to the surface in less than twenty minutes. The absence of high levels of lactic acid in the seals blood after such dives suggests that during them, the seals organs do not resort to the anaerobic metabolism observed in the laboratory, but are supplied with oxygen from the blood. The seals longer excursions underwater, during which it appears to be either exploring distant routes or evading a predator, do evoke the diving response seen in the laboratory. But why do the seals laboratory dives always evoke this response, regardless of their length or depth? Some biologists speculate that because in laboratory dives the seal is forcibly submerged, it does not know how long it will remain underwater and so prepares for the worst.

　　1. The passage provides information to support which of the following generalizations?

　　 Observations of animals physiological behavior in the wild are not reliable unless verified by laboratory studies.

　　 It is generally less difficult to observe the physiological behavior of an animal in the wild than in the laboratory.

　　 The level of lactic acid in an animals blood is likely to be higher when it is searching for prey than when it s evading predators.

　　 The level of lactic acid in an animals blood is likely to be lowest during those periods in which it experiences oxygen deprivation.

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