Use the figure below to answer the following question. A graph depicts the variation of price (per pound) on vertical axis with quantity supplied (thousands of bushels per week) on horizontal axis.The horizontal axis ranges from 0 through 20, in increments of 2 and the vertical axis ranges from 0 through 5, in increments of 1. The graph shows three increasing curves labeled S1, S2, and S3. S1 at the center has five plotted data points as (4 1), (8, 1.5), (12, 2) labeled a, (15, 3) labeled b, and (18, 4). To its right, is curve S2 with arrows pointing from S1 toward S2 and to its left, is curve S3 with arrows pointing from S1 toward S3. All the values used in description are approximate. The figure above shows three supply curves for wheat. Which of the following would cause the supply of wheat to shift from S1 to S3? Multiple Choice a tax on wheat production a subsidy for wheat production an increase in the price of wheat a decrease in the price of wheat