user: Question: Who was Mountains Classification in the race with Nick Frey as Youth Classification and Tom Zirbel as Points Classification?
Columns: ['Stage', 'Winner', 'General classification', 'Mountains classification', 'Points classification', 'Youth classification', 'Team Classification']
Types: ['real', 'text', 'text', 'text', 'text', 'text', 'text']
Sample row: [1.0, 'Tom Zirbel', 'Tom Zirbel', 'Tom Zirbel', 'Tom Zirbel', 'Nick Frey', 'Bissell']
SQL:

assistant: SELECT "Mountains classification" FROM "Table" WHERE "Youth classification" = 'Nick Frey' AND "Points classification" = 'Tom Zirbel';