Sí, tráigame una .
a. limonada b. carne c. postre

First of all, this sentence is given in the imperative mood. This mood is used when telling someone to do something in a direct manner. Put another way, sentences in the imperative mood are commands. On the other hand, limonada is the more logical answer and means lemonade. The other options are carne that means meat and postre that means dessert. Finally:

Sí, tráigame una limonada