which one of the following statements is correct???? plesse help

Which one of the following statements is correct? a. Having multicollinearity is one of the assumptions for ordinary least squares (OLS) estimation method. O b. Heteroskedasticity is one of the assumptions for ordinary least squares (OLS) estimation method Op-values cannot be used for hypothesis testing, Od in a regression model, when we include an irrelevant variable, this would increase the standard errors of beta estimates