8. A. As shown in Figure 3, in the rhombus $A B C D$ with side length 2, $B D=2, E$ and $F$ are moving points on $A D$ and $C D$ (including endpoints), and $A E+C F=2$. Then the range of the length of line segment $E F$ is . $\qquad$
8. A. $\sqrt{3} \leqslant E F \leqslant 2$.

From the given information, $\triangle A B D$ and $\triangle C B D$ are both equilateral triangles with side lengths of 2.
. Therefore, $C F=2-A E=A D-A E=D E$
$\Rightarrow \triangle B D E \cong \triangle B C F$
$\Rightarrow \triangle B E F$ is an equilateral triangle.
Thus, we only need to consider the range of the length of $B E$.
When the moving point $E$ reaches point $D$ or $A$, the maximum value of $B E$ is 2; when $B E \perp A D$, i.e., $E$ is the midpoint of $A D$, the minimum value of $B E$ is $\sqrt{3}$.
Therefore, $\sqrt{3} \leqslant E F \leqslant 2$.