Which of the Following Statements Is True

Which of the following statements is true:

A) Incremental costs vary in direct proportion to revenue.
B) A semi variable cost item can stay the same over large changes in revenue, but increase once a decision to increase capacity is implemented.
C) An opportunity cost will tend to vary in line with revenue.
D) A direct cost is a cost that can be traced to a particular cost object.
E) None of the above