1(B)
根据关键词“until the mid-twentieth”，“few jurisdictional disputes”定位原文
“since there were few standards of conduct that applied on the “open seas”, there were few jurisdictional conflicts between nations.”
原意重述如下
“few controls or restrictions applied to ocean areas”，即选项(B)
<中国人那句话”事不关己，高高挂起”，当然争论就少了>
2(C)
根据关键词“international law doctrines applicable before the mid-twentieth century”，“commercial activity within a particular nation’s territorial waters”定位原文
“Until the mid-twentieth century, ... limited sovereign rights over coastal waters. A nation had the right to include within its territorial dominion only a very narrow band of coastal waters (generally extending three miles from the shoreline), within which it had the authority but not the responsibility, to regulate all activities.”
同样为原意重述
“able but not required to place legal limits on such commercial activities5”
3(A)
根据关键词“before the mid-twentieth century”和“actions with respect to territorial and international waters”定位原文
“The lack of standards is traceable to popular perceptions held before the middle of this century. By and large, marine pollution was not perceived as a significant problem, in part because the adverse effect of coastal activities on ocean ecosystems was not widely recognized, and pollution caused by human activities was generally believed to be limited to that caused by navigation”，
和
“freedom to fish, or overfish, was an essential element of the traditional legal doctrine of freedom of the seas that no maritime country wished to see limited”
这些带色字体表明，重视程度不够，即
“managing ecosystems in either territorial or international waters was given low priority”
4(C)
根据关键词“an effect of the extension of territorial waters”定位原文
“And two recent developments may actually lead to future international rules
providing for ecosystem management. First, the establishment of extensive fishery zones extending territorial authority as far as 200 miles out from a country’s coast,
has provided the opportunity for nations individually to manage larger ecosystems.”
选项中的“the opportunity for some nations to manage large ocean ecosystems”表意相同，不用多说！
5(C)
根据关键词：时间“before the middle of the twentieth century”，对象“ nations failed to establish rules protecting their territorial waters”定位原文
“But, because this area of territorial dominion was so limited, most nations did not establish rules for management or protection of their territorial waters”，其中的this area指代” only a very narrow band of coastal waters (generally extending three miles from the shoreline)”
从以上信息可以推断出
“the size of the area that would be subject to such rules was insignificant”为最佳选项。