逾期付款的委婉提醒技巧 — 国际贸易选择题

以下哪句最适合用作首封催款函的开头，以体现逾期付款的委婉提醒技巧？ A. You must pay us immediately or we will take legal action against you. B. We would like to draw your attention to the fact that Invoice No. 208 has been overdue for 15 days. C. Why haven't you paid us yet? Your account is seriously overdue. D. Your payment is late and this has caused us great losses.