Let $\mathbf { r } = x \mathbf { i } + y \mathbf { j } + z \mathbf { k }$

Multiple Choice

Let $\mathbf { r } = x \mathbf { i } + y \mathbf { j } + z \mathbf { k }$ and $r = | \mathbf { r } |$ .
Find $\nabla \cdot ( 6 \mathbf { r } )$
Select the correct answer.

A) 6
B) 12
C) 18
D) 30
E) None of these