A is incorrect because the passage does not indicate whether or not there are chemicals outside of CFCs that are refrigerants. All we know is that CFC is a refrigerant. The second paragraph is the first place you see refrigerant mentioned and the last paragraph states that "in North America, CFCs were banned in the late 1970s, leading to [...] the development of more environmentally friendly refrigerant chemicals," which is after the time Molina and Rowland suggested that CFC production ceases and still gives no indication whether or not other refrigerants existed before then.
C is incorrect because there is no indication in the passage why CFCs were developed or if they were more energy-efficient refrigerants.
D is incorrect because of the last sentence of the passage. The cessation was due to it being banned in the late 1970s.
E is incorrect because (although it may be true) the passage does not indicate whether or not that exists. It only discusses that the use of CFCs has basically ceased. When going through this test, I chose this answer choice because my line of reasoning was, "well, which countries are included in this international agreement?" The answer is "I don't know because the passage doesn't indicate it." Additionally, there is no indication about what refrigerants look like today, we only know that the Montreal Protocol of 1987 occurred and a little before that time, development of more environmentally friendly refrigerant chemicals had begun.
B is the correct answer because by the time 1987 rolled around, North America was in the development of more environmentally-friendly/CFC-free refrigerant substitutes due to the CFC (AKA chlorine) ban in the late 1970s. The phrasing of this answer choice is confusing as it states, chemical refrigerants "release
fewer chlorine atoms into the stratosphere than CFCs do."
Fewer, in LSAT terms, indicates a decrease relative to something, like chlorine atoms released by CFCs; and that decrease includes anywhere from
zero to
just right below the amount of chlorine atoms CFCs released into the atmosphere.
Hopefully, this helps. Excuse any redundancies and spelling errors.