Two cones A and B have equal slant heights. The sum of the central angles of their lateral surface developments is $2 \pi$. Let their lateral surface areas be $S _ { \text{A} }$ and $S _ { \text{B} }$, and their volumes be $V _ { \text{A} }$ and $V _ { \text{B} }$. If $\frac { S _ { \text{A} } } { S _ { \text{B} } } = 2$, then $\frac { V _ { \text{A} } } { V _ { \text{B} } } =$\\
A. $\sqrt { 5 }$\\
B. $2 \sqrt { 2 }$\\
C. $\sqrt { 10 }$\\
D. $\frac { 5 \sqrt { 10 } } { 4 }$