Hi,
Concept: The given problem is based on 3 Dimensional Geometry.
Consider three axes in defined space be x, y & z in their positive directions then - x , -y & -z be their negative axes.
The coordinate of given point A(x1, y1, z1) = (1, -3, 4)
If we take the reflection of point A about xz - plane x and z coordinates will remain same and y-coordinate will give its reflection. It means the value of y-coordinate will be changed which will be +ve 3.
Hence, the reflection of A(1, -3, 4) will be A'(x2, y2,z2= (1, 3, 4).