The time had come to formulate a hypothesis. The investigators theorized that about
20 million years ago, the Mediterranean was a broad seaway linked to the Atlantic
by two narrow straits. Crustal movements closed the straits, and the landlocked
Mediterranean began to evaporate. Increasing salinity caused by the evaporation
resulted in the extermination of scores of invertebrate species. Only a few organisms
especially tolerant of very salty conditions remained. As evaporation continued, the
remaining brine (salt water) became so dense that the calcium sulfate of the hard
layer was precipitated. In the central deeper part of the basin, the last of the brine
evaporated to precipitate more soluble sodium chloride (salt). Later, under the weight
of overlying sediments, this salt flowed plastically upward to form salt domes. Before
this happened, however, the Mediterranean was a vast desert 3,000 meters deep.
Then, about 5.5 million years ago came the deluge. As a result of crustal adjustments
and faulting, the Strait of Gibraltar, where the Mediterranean now connects to the
Atlantic, opened, and water cascaded spectacularly back into the Mediterranean.
Turbulent waters tore into the hardened salt flats, broke them up, and ground them
into the pebbles observed in the first sample taken by the Challenger. As the basin
was refilled, normal marine organisms returned. Soon layers of oceanic ooze began to
accumulate above the old hard layer.
23. A ccording to paragraph 4, what caused most invertebrate species in the Mediterranean to become
extinct?
(A) The evaporation of chemicals necessary for their survival
(B) Crustal movements that connected the Mediterranean to the saltier Atlantic
(C) The migration of new species through the narrow straits
(D) Their inability to tolerate the increasing salt content of the Mediterranean
답이 D번인데요..
D번이 맞는건 알겠는데 보다 본질적인 이유는 B번 아닌가요?
B로인해서 salt가 들어오고 이걸 용해를 못시켜서 멸종한거니까... ㅠㅠㅠ
근본적인 원인 고르는 건 줄 알았는데...
제가 해석을 잘못한건가요??