The keys to the first blank are the clues “given their responsibilities as democratically elected officials” and “neglect to do everything they could.” These clues indicate that the first blank should have a negative connotation; a word that means something as simple as bad would eliminate thoughtful and intuitive, leaving irresponsible. Blanks (ii) and (iii) build on the idea set up in the first half of the sentence. The second blank describes the action that would be bad, so use something that means solve. Sustain and cultivate are the opposites of what’s needed for the second blank, leaving forestall. The last blank describes the type of problem, and entirely suggests it’s a solvable problem. Avoidable is close, and it helps the whole sentence make sense.