Find an Explicit Rule for the Nth Term of the Sequence

Multiple Choice

Find an explicit rule for the nth term of the sequence.
- $$- 1 , - 5 , - 25 , - 125 , \ldots$$

A) $a _ { n } = 5 \cdot - 1 ^ { n }$
B) $a _ { n } = - 1 \cdot 5 ^ { n - 1 }$
C) $a _ { n } = - 1 \cdot 5 ^ { n }$
D) $a _ { n } = 5 \cdot - 1 ^ { n + 1 }$