Answer
If $\theta_A$ is decreased, then part of the light refracts into material 3.
Work Step by Step
If $\theta_A$ is decreased, then the refracted angle in material 2 decreases.
Then the incident angle at the interface between materials 2 and 3 is decreased which would make the incident angle less than the critical angle.
In this case, part of the light refracts into material 3.
If $\theta_A$ is decreased, then part of the light refracts into material 3.
