Clerk: Good morning. Can I help you? Mr. Smith: Yes Id like a ticket to New York 9:15 to

Clerk: Good morning. Can I help you？ Mr. Smith: Yes, I"d like a ticket to New York 9:15 tomorrow morning. Clerk: ______？ Mr. Smith: Single, please.

A．Single or two

B．Single or return

C．Single or double

D．Single or back