CREATE TABLE table_43173 ("Name" TEXT, "Position" TEXT, "Number" TEXT, "School/Club Team" TEXT, "Season" TEXT, "Acquisition via" TEXT)

What season did School/Club Team, East have an Acquisition via of trade?
SELECT "Season" FROM table_43173 WHERE "Acquisition via" = 'trade' AND "School/Club Team" = 'east'
SELECT "Season" FROM "table_43173" WHERE "Acquisition via" = 'trade' AND "School/Club Team" = 'east'