9. Let $S _ { n }$ denote the sum of the first $n$ terms of the geometric sequence $\left\{ a _ { n } \right\}$. If $S _ { 2 } = 4 , S _ { 4 } = 6$, then $S _ { 6 } =$ A. 7 B. 8 C. 9 D. 10
9. Let $S _ { n }$ denote the sum of the first $n$ terms of the geometric sequence $\left\{ a _ { n } \right\}$. If $S _ { 2 } = 4 , S _ { 4 } = 6$, then $S _ { 6 } =$\\
A. 7\\
B. 8\\
C. 9\\
D. 10