Final answer:
The correct answer is option A) The Voice.
Step-by-step explanation:
Patti LaBelle served as a guest mentor to singers on the popular TV show competition The Voice. Specifically, she appeared alongside Christina Aguilera, who has been a coach on the show for several seasons.
The Voice is known for its format of blind auditions and battles, with successful contestants moving on to live performances and the possibility of winning the competition with the help and guidance of their coach and guest mentors like Patti LaBelle.