[单选题]The young shop assistant told him the total price, ＄37.60. The boy was instantly disappointed and said he had only been given ＄20. He took out one thing at a time until he got down to his ＄20. With eyes full of tears, he asked if he could phone his mum to pick him up. When he got through, it appeared that even this was inconvenient for his mother. 阅读选择 At the checkout, the boy found that he （）. A did not have enough money  B did not have his money on him  C forgot to ask his mum for money  D had lost his money in the store