Question: What actress and singer who played a starring role in "Grease" was a special guest during the Mormon Tabernacle Choir's 2015 Christmas shows?
{'answer': 'Laura Ann Osnes', 'supporting_facts': [['Hallelujah! (Mormon Tabernacle Choir album)', 0], ['Hallelujah! (Mormon Tabernacle Choir album)', 1], ['Laura Osnes', 0], ['Laura Osnes', 1]]}