Consider the regression model:

testscore=β1+β2IQ+β3male+β4(IQ×male)+u

where,   testscore  = students’ test score 

              IQ       = student’s IQ

              male     = 1 if student is male, = 0 if student is female

Based on this model, how do we assess the statistical significance of IQ?

A. Test H0 : β2 = β4 = 0 , Ha : H0 is false

B. Test H0 : β2 = 0 , Ha : H0 is false

C. First test  H0 : β2 = 0 , Ha : H0 is false. If we do not reject, then we test ,H0 : β4 = 0 Ha : H0 is false

D. First test H0 : β2 = 0 , Ha : H0 is false. If we reject, then we test ,H0 : β4 = 0 Ha : H0 is false