If \(x < y < z\) and the average (arithmetic mean) of \(x\), \(y\), and \(z\) is \(y\), which of the following must be true?
(A)\(z - y = 2\) (B)\(x + y + z = 3y\) (C)\(x + y < z\) (D)\(x + y = z\) (E)\(2z = 3y\)
B