|Question 23Verbal

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In 1974, Mexican chemist Mario Molina and US chemist F. Sherwood Rowland discovered that chemicals called CFCs were harmful to the ozone layer. Their research was extremely influential in the fight against CFCs.        it laid the foundation for a 1987 treaty that phased out the use of CFCs across the globe.
Which choice completes the text with the most logical transition?
Specifically,
A
Regardless,
B
Earlier,
C
However,
D