The correct dining etiquette that should be followed at an elegant restaurant is:
- No poner los codos sobre la mesa.
Explanation:
"No poner los codos sobre la mesa" that translates <em>do not put the elbows on the table </em>is a norm of etiquette used in elegant places, the other options translates: "no dejar propina para al camarero": <em>do not leave a tip for the waiter</em>, "no hacer reserva"
: <em>do not make a reservation</em> and "no saludar al camarero": <em>do not greet the waiter</em>, are complete opposites to the etiquette, reason why are discard.
Ella la compra. I don't think there are two object pronouns that can be used in this one sentence, so I would assume that the second pronoun was for another sentence.
see how gracias made sense in that sentence make sure next time when you get a question like this again make sure that you think over the dialogue again and see which word would fit into that sentence