–– Clerk: Good morning. Can I help you？–– Thompson: Yes, I’d like a ticket to New York

–– Clerk: Good morning. Can I help you？

–– Thompson: Yes, I’d like a ticket to New York 9: 15 tom rrow morning.

–– Clerk: ____

–– Thompson: Single, please.

A: Single or two？

B: Single or double？

C: Single or back？

D: Single or return？