I want an answer please

15. Which of the following represents a regression model? a. = f(X, X2, ,Xk) b. Y = f(X, X, , Xk)+ c. Y = f(X1, X2, ..., xk) d. Y = f(X1, X2, ..., Xk) +

15. Which of the following represents a regression model? a. Y=f(X1,X2,,Xk) b. Y=f(X1,X2,,Xk)+ c. Y=f(X1,X2,,Xk) d. Y=f(X1,X2,,Xk)+