Right answer:
c. La acera
La acera translates into the sidewalk and is an area along the the side of a street that has a hard surface, used by people who are walking. It is common that you find coffee tables along the the side of a street. Finally, our sentence can be written and translated as follows:
IN SPANISH:
Las mesas del café Luna están en la acera
IN ENGLISH:
Luna coffee tables are on the sidewalk