The electric field on the dashed line in Figure 19-37 vanishes at infinity, but also at two

Question:

The electric field on the dashed line in Figure 19-37 vanishes at infinity, but also at two different points a finite distance from the charges. Identify the regions in which you can find E = 0 at a finite distance from the charges: region 1, to the left of point A; region 2, between points A and B; region 3, between points B and C; region 4, to the right of point C.

Figure 19-37