Final answer:
The phrase "a nuestros abuelos" will be replaced by the indirect object pronoun "les."
Step-by-step explanation:
In the sentence "Nosotros traemos la comida a nuestros abuelos," the phrase that will be replaced with an indirect object pronoun is "a nuestros abuelos."
The indirect object pronoun that will be used is "les."
Therefore, the sentence with the indirect object pronoun would be "Nosotros les traemos la comida."
Learn more about Spanish Indirect Object Pronouns