The five hundred largest manufacturing firms in the United States produce goods that are worth almost as much as that of the four hundred thousand firms that remain.
(A) that are worth almost as much as that of the four hundred thousand firms that remain
(B) of a worth that is almost as much as that of the four hundred thousand firms that remain
(C) almost as much in worth as those of the remaining four hundred thousand firms
(D) almost as much in worth as that of the remaining four hundred thousand firms.
(E) worth almost as much as those of the remaining four hundred thousand firms

Need a good explanation. Can anyone help?