Consider the following sample regression function (SRF) estimated from a sample of 20 observations (n=20):

y= 0.08 4.72x1- 3.66x2+4.03x3(3.21) (2.77) (1.21) (4.52)

.

The standard errors are in parentheses. Which of the following is a correct statement

about the statistical significance of the variables?

a) The variable x1can significantly explain y at 5% level. b) The variable x2can significantly explain y at 1% level.

c) The variable x1can significantly explain y at 1% level. d) The variable x3can significantly explain y at 5% level.