3D points

Consider the points A(2, 4, 6), B(-2, -4, -2), C(4, 6, 4) andD(8, 14, 12).

Which of the following statements is/are correct? 1. The points are the vertices of a rectangle ABCD. 

2. The mid-point of AC is the same as that of BD.

Select the correct answer using the code given below:

The number of spheres of radius r touching the coordinate axes is

The xy-plane divides the line segment joining the points (-1, 3, 4) and (2, -5, 6)

The locus of a point P(x, y, z) which moves in such a way that z = 7 is a

What is the number of possible values of k for which the line joining the points (k, 1, 3) and (1, - 2, k + 1) also passes through the point (15, 2, - 4)??