The narrator can hear the thoughts of too many other characters.
I think the answer is B. People concerned about the environment are likely to buy eco-cars. This may or may not be the correct answer. I think I got this wrong. Sorry if the answer isn't correct.
Mustufa ran the 100-meter and 200-meter races (but the one he had trained for the hardest was the 400-meter competition).
This is the only answer that is grammatically correct. Parentheses cannot just be place anywhere in a sentence. They are used to add extra information for clarity or information that is an aside). An aside is something that is not the main part of the discussion. In this sentence, the main point is that Mustufa ran the sprint races. The extra information is that he trained for the mid-distance race.
