Windy City manufactures decorative weather vanes that have a standard materials cost of two pounds of raw materials at $2 per pound for each completed vane. During September 500 pounds of raw materials costing $4 per pound were used in making 450 weather vanes. The materials price and quantity variance are: O a. Material Price Variance 500 U, Material Quantity variance 400 F O b. Material Price Variance 1,000 F, Material Quantity variance 800 F O c. Material Price Variance 1,000 U, Material Quantity variance 800 F O d. Material Price Variance 500 F, Material Quantity variance 400 U