The correct option is A Cellulose
Cell wall is the outermost protective double layered structure. Each cell of Spirogyra is surrounded by two layered cell wall. The inner layer of which is made of cellulose and the outer layer contains pectose. The outermost lining of pectose turns into pectin and get dissolved in water to form mucilage, which surrounds the filament and forms mucilagenous sheath.