Which of the following statements is true about multiple linear regression output (assuming that Y is the dependent variable, and X1 is an independent variable): a=0.05 Group of answer choices A negative coefficient on X1 means that X1 should be removed from the model. A p-value less than 0.05 for X1 implies that X1 causes Y. A p-value less than 0.05 for X1 indicates a significant relationship between X1 and Y. A negative coefficient on X1 implies a nonlinear relationship between X1 and Y