Which is the correct statement?

a. DuPont analysis decomposes ROE into net profit margin, asset turnover and PE ratio

b. When evaluating a projects NPV, we should always use firms WACC as a discount rate.

c. Days payable outstanding (DPO) captures how long a firm takes to collect its credit sales.

d. Security Market Line (SML) is derived from capital asset pricing model (CAPM)