(A) Insurance companies often fail to pay the sums dictated in verdicts reached against individual defendants. - Don't have to assume this, argument holds even if they fail always or they don't fail at all.
(B) The extent to which the payment is expensive to the defendant should be a consideration in the determination of awards.
- If we negate it , and the extent of expensiveness isn't a consideration anymore , then woaahhh, what if lets say for individual earning 1000$ , he has to pay 20% of the income which will be 200$. But for a corporation having revenue of 100 Million dollars [mind you its not income, its revenue, so basically company gets less than this after subtracting costs], 20% is a looooottt of moneyyyy , maybe more than what would have been ,had the verdict been based on the company's ability to pay[taking profits into consideration

]. in that case verdict shouldn't be based on the proportionally to the revenue.
Hence our answer

(C) Corporations are responsible for at least as many of the problems in our society as are individuals.
- uhm what if they are responsible for fewer problems ? still argument holds that we can charge verdict proportionally according to their revenue
(D) No punishment is too large for the truly guilty.
- Don't have to assume that
no punishment is too large for the
truly guilty
(E) The justice system has always been effective in collecting large sums imposed on defendants
- Even if it is 90-80% effective , it still is good isn't it ? :p , definitely not an assumption