Rotate the Axes to Eliminate The $x y$ -Term in the Following Equation

Multiple Choice

Rotate the axes to eliminate the $x y$ -term in the following equation.
$$- 30 x ^ { 2 } + 20 \sqrt { 3 } x y - 10 y ^ { 2 } - 20 x - 20 \sqrt { 3 } y = 0$$

A) $\left( y ^ { \prime } \right) ^ { 2 } + x ^ { \prime } = 0$
B) $- 10 \sqrt { 3 } \left( y ^ { \prime } \right) ^ { 2 } - 10 \sqrt { 3 } x ^ { \prime } = 0$
C) $- 10 \left( x ^ { \prime } \right) ^ { 2 } + 10 y ^ { \prime } = 0$
D) $- \frac { \left( y ^ { \prime } \right) ^ { 2 } } { 10 } - \frac { x ^ { \prime } } { 10 } = 0$
E) $- \frac { \left( x ^ { \prime } \right) ^ { 2 } } { 20 } - \frac { y ^ { \prime } } { 20 } = 0$