"La comida es para los reyes."
If the dropdown includes "pets" as an answer, why not "The food is for the pets?"
Now, does this mean "the food is for [king #1 and king #2]" or could it also mean "the food is for the [King and Queen]". Is reina the feminine form of rey? If you want to address the king and queen, could you say something along the lines of "the monarchs"?
Could it convey the meaning that it is fit for kings? As for reyes: I remember that, when I was 6 years old, I stayed with my parents in Santiago de Compostela in Hostal de los reyes catolicos and sleeping in a four poster bed... http://www.spain.info/fr/conoce/monumentos/coruna_a/hostal_de_los_reyes_catolicos.html
You stayed there? It seems it's not a hotel anymore. Jealous! Or is it still a hotel?
This is an idiom, as you guessed it translates to the english "Food fit for a King"