Write the Expression for the General (Or Nth)termrm $\mathbf { a } _ { \mathbf { n } } ,$

Multiple Choice

Write the expression for the general (or nth) termrm, $\mathbf { a } _ { \mathbf { n } } ,$ , of the geometric sequence.
- $- \frac { 1 } { 3 } , - \frac { 1 } { 27 } , - \frac { 1 } { 243 } , - \frac { 1 } { 2187 } , \ldots$

A) $a _ { n } = \left( - \frac { 1 } { 3 } \right) ^ { n - 1 } + \frac { 8 } { 27 }$
B) $a _ { n } = - \frac { 1 } { 3 } + \frac { 8 } { 27 } ( n - 1 )$
C) $a _ { n } = - \frac { 1 } { 3 } + \frac { 1 } { 9 } ( n - 1 )$
D) $a _ { n } = - \frac { 1 } { 3 } \left( \frac { 1 } { 9 } \right) ^ { n - 1 }$