Ten fabrics of different colors are displayed on ten racks in a cloth store. The racks are placed one after another and numbered consecutively from one to ten. Each rack contains fabric of a single color. One fabric is green , two fabrics are brown , three fabrics are purple and remaining four fabrics are red. If a purple fabric is on rack two and red fabrics are on racks three and four , the green fabric must be on which of the following racks?