Given that the geometric sequence $\left\{ a _ { n } \right\}$ has the sum of its first 3 terms equal to 168 , and $a _ { 2 } - a _ { 5 } = 42$ , then $a _ { 6 } =$ A. 14 B. 12 C. 6 D. 3
Given that the geometric sequence $\left\{ a _ { n } \right\}$ has the sum of its first 3 terms equal to 168 , and $a _ { 2 } - a _ { 5 } = 42$ , then $a _ { 6 } =$
A. 14
B. 12
C. 6
D. 3