Answer: A ellos les gusta comer enchiladas
Step-by-step explanation:
i will take each sentence and describe why is correct or not.
"A ellos les gusta las enchiladas."
Here you can see that "...Gusta Las..." in this case "gusta" is in singular, and the word right next to it "las" is a plural pronoun, so this is incorrectly written.
"Ellos gusta comer enchiladas."
Here we do not have any pronoun, this is incorrectly written.
"Ellos gustan las enchiladas."
Here you can see that "gustan" is correctly in plural, but now we don't have the pronoun before it, so this is incorrect.
"A ellos les gusta comer enchiladas"
Now we have all the pronoun, in this case we have "gusta" again, that is in singular, but it is followed by a non conjugated action "comer", so in this case it is cohesive, so this is correctly written.