QUESTION 49 0.375 points Save Answer If Xit is correlated with Xis for different values of s and t, then: Oa. Xit is said to be i.i.d. Ob. the OLS estimator can be computed. Oc. you need to use an AR(1) model. Od. you need to include time fixed effects to eliminate such correlation. Oe. All of the above. Of. None of the above