2. As shown in Figure 1, line $k \parallel l$,
$$
\begin{array}{l}
\angle 4-\angle 3=\angle 3-\angle 2 \\
=\angle 2-\angle 1=d>0, \text { where } \\
\text { among, } \angle 3<90^{\circ}, \angle 1=50^{\circ} .
\end{array}
$$

Then the maximum possible integer value of $\angle 4$ is ( ).
(A) $107^{\circ}$
(B) $108^{\circ}$
(C) $109^{\circ}$
(D) $110^{\circ}$
2. C.
$$
\begin{array}{l}
\text { Given } \angle 3=50^{\circ}+2 d<90^{\circ} \Rightarrow d < 20^{\circ} \\
\Rightarrow \angle 4=50^{\circ}+3 d<50^{\circ}+3 \times 20^{\circ}=110^{\circ}
\end{array}
$$
$\Rightarrow \angle 4$ The maximum possible integer value is $109^{\circ}$.