看了前辈们的讨论仍然不理解啊，麻烦NN们再指点一下！
14. Intended primarily to stimulate family summer travel, the new airfare, which allows both an adult and a child to fly for the price of one ticket, and also shortens the advance-purchase requirement for family travel to a minimum of seven days rather than fourteen.
(A) and also shortens the advance-purchase requirement for family travel to a minimum of seven days rather than
(B) and also lessens the advance-purchase requirement for family travel to a seven-day minimum from
(C) also shortens the advance-purchase requirement for family travel to a minimum of seven days rather than that of
(D) also lessens the advance-purchase requirement for family travel to a seven-day minimum from
(E) also shortens the advance-purchase requirement for family travel to a minimum of seven days rather than
答案E，为什么不能选D呢？ | 
