Solve the Problem $x ^ { 2 } + y ^ { 2 } + z ^ { 2 } = 16$

Multiple Choice

Solve the problem.
-Find the mass of the solid in the first octant between the spheres $x ^ { 2 } + y ^ { 2 } + z ^ { 2 } = 16$ and $x ^ { 2 } + y ^ { 2 } + z ^ { 2 } = 100$ if the density at any point is inversely proportional to its distance from the origin.

A) $28 \mathrm { k } \pi$
B) $168 \mathrm { k } \pi$
C) $14 \mathrm { k } \pi$
D) $21 \mathrm { k } \pi$