CREATE TABLE table_19834 ("Stage" FLOAT, "Winner" TEXT, "General classification" TEXT, "Points classification" TEXT, "Mountains classification" TEXT, "Combination classification" TEXT, "Team classification" TEXT)

If winner is alejandro Valverde and the points Classification is by Erik Zabel, who is the mountain classification?
SELECT "Mountains classification" FROM table_19834 WHERE "Winner" = 'Alejandro Valverde' AND "Points classification" = 'Erik Zabel'
SELECT "Mountains classification" FROM "table_19834" WHERE "Points classification" = 'Erik Zabel' AND "Winner" = 'Alejandro Valverde'