Let $x , y$ and $z$ be positive real numbers. Suppose $x , y$ and $z$ are the lengths of the sides of a triangle opposite to its angles $X , Y$ and $Z$, respectively. If
$$\tan \frac { X } { 2 } + \tan \frac { Z } { 2 } = \frac { 2 y } { x + y + z }$$
then which of the following statements is/are TRUE?\\
(A) $2 Y = X + Z$\\
(B) $Y = X + Z$\\
(C) $\tan \frac { X } { 2 } = \frac { x } { y + z }$\\
(D) $x ^ { 2 } + z ^ { 2 } - y ^ { 2 } = x z$