Problem 14. (2.5 %) Let X and Y be two continuous random variables. Then,
(A) E[XY] = E[X]E[Y]
(B) E[X² + Y²] = E[X²] + E[Y²]
(C)f_X+Y(x+y)=f_X(x)f_Y(y)
(D) var(X+Y)=var(X)+var(Y)

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