逾期付款的委婉提醒技巧 — 国际贸易填空题

出口商就 Invoice No.3158 的逾期货款向买方发出首封催款函。为体现委婉提醒技巧，应避免指责语气，将逾期归因于可能的无意疏忽。请补全函中空缺处：We hope to receive your remittance soon. We are sure that the delay in settling this invoice ____ (填 A 或 B)。A. may have simply escaped your attention B. is clearly a serious breach of your promise