Final answer:
The correct -ER conjugation for Ellos/Ellas is -en.
Step-by-step explanation:
For the pronoun Ellos/Ellas, the correct -ER conjugation is option C: -en.
For example, if you have the verb comer (to eat), the correct conjugation for Ellos/Ellas would be comen (they eat).
Therefore, the correct answer is C: -en.
Learn more about Conjugation of -ER verbs in Spanish