Find an Explicit Rule for the Nth Term of the Arithmetic

Multiple Choice

Find an explicit rule for the nth term of the arithmetic sequence.
- $1,3,5,7 , \ldots$

A) $a _ { n } = 1 + 2$
B) $a _ { n } = 1 + 2 ( n + 1 )$
C) $a _ { n } = 1 + 2 ( n )$
D) $a _ { n } = 1 + 2 ( n - 1 )$