G12 Physics question involving a rectangular block of glass and a laser.?

(a)
For path A, at the top boundary the angle of incident is smaller than the critical angle.  Most of the light refracts and exits at the top of the glass block.  Part of the light reflects and then exits the left side of the glass block.
For path B, at the top boundary the angle of incident is smaller than the critical angle.  The light totally reflects and then exits the left side of the glass block.

(b)
Refer to Figure 1 below.

(c)
Refer to Figure 2 below.

(d)
Path B will produce the brightest beam exiting the left side of the block. This is because most of the light along path A exits the top of the glass block.