What is the the coordination number of a particle in simple cubic close packed structure?

The coordination number in a crystal lattice is defined as the number of nearest neighbors to a particle.

In a simple cubic structure, each atom is positioned at the corners of a cube. A central atom contacts six adjacent atoms: one each along the positive and negative directions of the $x$, $y$, and $z$ axes.

Thus, the coordination number is $6$.

Although simple cubic is not a close-packed structure like FCC or HCP (which have coordination number $12$), the result remains consistent.

Final answer: $\boxed{C}$