Question

in 1974 mexican chemist mario molina and us chemist f. sherwood rowland discovered what 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.
23 mark for review
which choice completes the text with the most logical transition?
a regardless,
b specifically,
c however,
d earlier,

Explanation:

The sentence before the blank states that the research was "extremely influential in the fight against CFCs", and the part after the blank says "it laid the foundation for a 1987 treaty...". We need a transition word that shows a further explanation or specification of how the research was influential. "Specifically" (Option B) fits here as it elaborates on the impact of the research. "Regardless" (A) implies despite something, which doesn't fit. "However" (C) is for contrast, and "Earlier" (D) refers to time, neither of which fit the context of elaborating on the research's impact.

Answer:

B. Specifically