Answer: The prepositional phrase that can be added to the sentence provided is "with his friends".
Step-by-step explanation: A prepositional phrase is a phrase that includes a preposition, its object and, in some cases, words that modify that object. Moreover, a prepositional phrases usually modifies a verb or a noun. "With his friends" is the only prepositional phrase among the options; therefore, it is also the only one that can be added to the sentence "Kenny played video games". "With his friends" has been introduced by the preposition "with". In contrast, neither of the other phrases has been introduced by a preposition.