63/29 答案为什么是E? 没看出来，请各位帮帮忙，多谢～～

Passage 29 (29/63)

Studies
of the Weddell seal in the laboratory have described the physiological
mechanisms that allow the seal to cope with the extreme oxygen deprivation that
occurs during its longest dives, which can extend 500 meters below the ocean’s
surface and last for over 70 minutes. Recent field studies, however, suggest
that during more typical dives in the wild, this seal’s physiological behavior is
different.

In the laboratory,
when the seal dives below the surface of the water and stops breathing, its
heart beats more slowly, requiring less oxygen, and its arteries become
constricted, ensuring that the seal’s blood remains concentrated near those
organs most crucial to its ability to navigate underwater. The seal essentially
shuts off the flow of blood to other organs, which either stop functioning
until the seal surfaces or switch to an anaerobic (oxygen-independent)
metabolism. The latter results in the production of large amounts of lactic acid (lactic
acid: n.乳酸) which can adversely affect the pH of the seal’s blood, but since
the anaerobic metabolism occurs only in those tissues which have been isolated
from the seal’s blood supply, the lactic acid is released into the seal’s blood
only after the seal surfaces, when the lungs, liver, and other organs quickly
clear the acid from the seal’s bloodstream.

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 seal’s blood after such dives
suggests that during them, the seal’s organs do not resort to the anaerobic
metabolism observed in the laboratory, but are supplied with oxygen from the
blood. The seal’s 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 seal’s 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.

5.     According
to the author, which of the following is true of the laboratory studies
mentioned in line 1?（此题狡猾！）

(A) They fail
to explain how the seal is able to tolerate the increased production of lactic
acid by organs that revert to an anaerobic metabolism during its longest dives
in the wild.

(B) They
present an oversimplified account of mechanisms that the Weddell seal relies on
during its longest dives in the wild.

(C) They
provide evidence that undermines the view that the Weddell seal relies on an
anaerobic metabolism during its most typical dives in the wild.

(D) They are
based on the assumption that Weddell seals rarely spend more than twenty
minutes underwater on a typical dive in the wild.（E）

我知道了。第三段The seal’s 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.

真的狡猾。

我知道了。第三段The seal’s 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.

真的狡猾。