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.
--8, -24, -72, -216, -648,. . .

A) $a _ { n } = - 8 ( 3 ) ^ { n }$
B) $a _ { n } = - 8 ( 3 n )$
C) $a _ { n } = - 8 ( 3 ) ^ { n - 1 }$
D) $a _ { n } = a _ { 1 } + 3 ^ { n }$