(A) A successive discount of 12% and 15% on any number of toys purchased.
(B) successive discount of 15%, 10% and 2% on any number of toys purchased.
(C) 40% off on the first 3 toys, and 15% off on each subsequent toy.
(D) 2 toys free on purchase of 10 toys. A lady customer wants to buy 10 toys.
Which of the above schemes is most beneficial to her?