Two male singers, Peer and Shaer; two female singers Rina and Vina; two male dancers Tapu and Wahed; and two female dancers Queen and Usha, are the eight entertainers who are to perform at the Bengal Theater on a certain night. Each entertainer is to perform alone and only once that night. The entertainer may perform in any order that conforms to the following restrictions: The performances by singers and the performances by the dancers must alternate throughout the evening. The first performance that evening must be by a female entertainer, and the second performance by a male entertainer. The final performance must be by a male singer. If Rina is to perform fourth, which of the following must perform sixth?