Final answer:
The sentence is already in the plural form in French.
Step-by-step explanation:
In French, the sentence "Elle écoute une émission radiophonique avec lui" is already in the plural form. It translates to "They listen to a radio program with him." In this sentence, the subject pronoun "elle" (she) has been changed to "they" to make it plural.
Learn more about Pluralization in French