Rosemary concludes that "cheques would be no use" in this situation because:
D. because Miss Smith would be unlikely to have a bank account.
This inference is drawn from the context, where Rosemary is contemplating giving Miss Smith money after recognizing her beauty and wanting to assist her. Given Miss Smith's circumstances as someone asking for money on the street, it is reasonable for Rosemary to assume that she may not have a bank account to cash a cheque.