Margo, Inc. purchased goods from Fairlane Industries. If Margos accounts show a Purchase Discount account related to this purchase, which of the following is true?

a. Margo considers purchase discounts lost as a financial expense. b. Margo uses the gross method and a periodic inventory system. c. Margos management can measure inefficiency by holding management responsible for discounts not taken. d. All of these are correct regarding Margo, Inc

Why the option b is not answer and the option c is the answer?

plz kindly explain in detail !!

Thank you for your answer in advance