Last month Jones Hat Company sold 100 hats at $10 each. This month it raised the price of hats to $11 and sold 101 hats. This result indicates that another factor, such as income, changed, shifting the demand curve for hats to the right. the demand curve for hats is upward sloping. the law of demand is violated. another factor, such as income, changed, shifting the demand curve to the left. the supply curve of hats shifted upward.