The Wronskian of the Vector Functions $X _ { 1 } = \left( \begin{array} { c } 1 \\- 1\end{array} \right) e ^ { - 2 t }$

Multiple Choice

The Wronskian of the vector functions $X _ { 1 } = \left( \begin{array} { c } 1 \\- 1\end{array} \right) e ^ { - 2 t }$ and $X _ { 2 } = \left( \begin{array} { l } 3 \\5\end{array} \right) e ^ { 6 t }$ is

A) $8 e ^ { 4 t }$
B) $2 e ^ { 4 t }$
C) $- 8 e ^ { 4 t }$
D) $- 2 e ^ { 4 t }$
E) $15 e ^ { 4 t }$