Break-Even Analysis Usually Assumes All of the Following Except

Break-even analysis usually assumes all of the following except:

A) in the short run,there is no distinction between variable and fixed costs.
B) revenue and cost curves are straight-lines throughout the analysis.
C) there appears to be perfect competition since the price is considered to remain the same regardless of quantity.
D) the straight-line cost curve implies that marginal cost is constant.
E) both c and d