Find a General Term A_n for the Geometric Sequence $$8 , - 4,2 , - 1 , \frac { 1 } { 2 } ,$$

Multiple Choice

Find a general term a_n for the geometric sequence.
- $$8 , - 4,2 , - 1 , \frac { 1 } { 2 } ,$$

A) $a _ { n } = \frac { 1 } { 8 } ( - 2 ) n - 1$
B) $a _ { n } = 6 \left( - \frac { 1 } { 4 } \right) ^ { n - 1 }$
C) $a _ { n } = 8 \left( \frac { 1 } { 2 } \right) ^ { n - 1 }$
D) $a _ { n } = 8 \left( - \frac { 1 } { 2 } \right) ^ { n - 1 }$