Developing skills to identify premises and conclusions

@Joshua, (C) is incorrect because the argument here is limited to small companies. Therefore, no information about large companies is needed. It doesn't matter if they're better or worse. (D) is correct because since the five companies are lumped together, the argument is making the assumption that the employee's company comprises a large chunk of the 60 percent. Therefore, it's not necessary that the other four companies don't comprise almost all of the 60 percent. If they did, the employee's company might only pollute one or two percent of the total amount, and the argument would fall apart.