Q = -6,500 - 100P_(A) + 50P_(B) + 0.3I + 0.2A; R^(2) = 0.12, (2,500)(50)(20)(0.2)(0.08) where Q is the quantity demanded of good A; P_(A) = $10, price of good A; P_(B) = $8, price of good B; I = $12,000, per capita income; and A = $20,000, monthly advertising expenditures. Standard errors of the estimated coefficients are provided in the parenthesis. For example, 50 is the standard error of the coefficient on P_(A). Which of the variables does not pass the t-test at the 0.05 level of significance?