Question

following a spike in respiratory illnesses in 2015, the city of port elsin ___ a temporary restriction on diesel - powered buses in its central district. health department reports showed a 22 percent reduction in airborne particulates within six months. nevertheless, officials acknowledged that improvements could not be attributed solely to the policy, as a mild winter and reduced industrial output likely contributed. the episode illustrates the difficulty of isolating cause and effect in urban health interventions. 18 which choice completes the text so that it conforms to conventions of standard english? a implemented b had implemented c will implement d has implemented

Explanation:

To determine the correct verb tense, we analyze the context. The events (spike in 2015, restriction implementation, and subsequent health reports) are in the past. The simple past tense ("implemented") is appropriate here as it describes a past action. "Had implemented" (past perfect) would imply the action happened before another past action, but there's no such sequence. "Will implement" (future) and "has implemented" (present perfect) don't fit the past - tense context of the text.

Answer:

A. implemented