In a regression analysis of a first-order model involving 3 predictor variables and 25 observations, the following estimated regression equation was developed. ŷ = 10 - 18x1 + 3x2 + 14x3 also, the following standard errors and the sum of squares were obtained. sb1 = 3 sb2 = 6 sb3 = 7 sst = 4800 sse = 1296 if you want to determine whether or not the coefficients of the independent variables are significant, the critical t value at α = .05

a. 2.064.
b. 2.086.
c. 2.080.
d. 2.060.