Use the following to answer the question on the basis of the following regression equation. (Standard errors in parentheses, n = 200.) Q = -6,500 - 100PA + 50PB + .3I + .2A; R2 =.12 (2,500) (50) (30) (.1) (.08) where Q is the quantity demanded of good A; PA = $10, price of good A; PB = $8, price of good B; I = $12,000, per capita income; and A = $20,000, monthly advertising expenditures. Which of the variables does not pass the t-test at the .05 level of significance?