Which of the following characters is NOT playable in "Resident Evil 6"?

Jill Valentine is not playable in Resident Evil 6 because her story arc is concluded in Resident Evil 5. In that game, Jill is rescued from Wesker's control and plays a significant role in defeating him. As a result, Resident Evil 6 focuses on different characters and their interconnected storylines, leaving Jill's playable character option omitted in order to explore new narratives and expand the Resident Evil universe.