8. If $\odot O$ is inscribed in $\triangle A B C$ and touches the three sides at points $X, Y, Z$. Then, $\triangle X Y Z$ satisfies ( ).
(A) Each angle is equal to $60^{\circ}$
(B) One is an obtuse angle, the other two angles are acute
(C) It is similar to $\triangle A B C$
(D) Each angle is equal to half the sum of two angles in $\triangle A B C$
8. It can be proven that points $O, Y, X, B$ are concyclic, thus
$$
\angle O X Y=\angle O B Y=\frac{1}{2} \angle A B C \text {. }
$$

Similarly, $\angle O X Z=\angle O C Z=\frac{1}{2} \angle A C B$.
Therefore, $\angle Y X Z=\frac{1}{2}(\angle A B C+\angle A C B)$.
Similarly, $\angle X Z Y=\frac{1}{2}(\angle C A B+\angle A C B)$,
$$
\angle Z Y X=\frac{1}{2} \cdot(\angle C A B+\angle A B C) \text {. }
$$

Choose D.