Answer: B. protestara
Sería ideal que todo el mundo protestara contra la polución.
Translation: It would be ideal, that everybody to protest against pollution.
Explanation:
The classic use of imperfect subjunctive in Spanish is with the conditional (sería) in the main sentence to express that at the moment of speaking what is said in the sentence it is contrary to reality.
[tex]\textit{\textbf{Spymore}}[/tex]
