Find the Requested Partial Derivative $\frac { \partial w } { \partial x }$

Multiple Choice

Find the requested partial derivative.
- $\frac { \partial w } { \partial x }$ if $w = x ^ { 3 } + y ^ { 3 } + z ^ { 3 } + 15 x y z$ and $\left( \frac { \partial y } { \partial x } \right) ^ { 2 } + \left( \frac { \partial z } { \partial x } \right) ^ { 2 } = 0$ .

A) $15 x ^ { 2 }$
B) $3 x ^ { 2 }$
C) $3 \left( x ^ { 2 } + y ^ { 2 } + z ^ { 2 } \right)$
D) $15 \left( x ^ { 2 } + y ^ { 2 } + z ^ { 2 } \right)$