Suppose we have data on sales of mulled wine (warm wine with added spices like cinnamon and claves) and the prices of mulled wine at the annual Christmas fair in a city each year, aver three decades. We wish to estimate how demand for mulled wine depends an its price, but we are concerned that the price af mulled wine will be higher in years when the temperature at the fair was particularly cold. What would be a sensible instrument for the price of mulled wine? a. Population of the city that year b. Thewholesale price of spices in the city that year c. The oneyearlagged price of mulled wine d. Lagged mulled wine sales