You have the following expression:
[tex]a_n=-5+2(n-1)[/tex]Notice that for each value of n = 1,2,... the value of an is two units greater then the previous one. Moreover, -5 is a constant and for n = 1, an = a1 = 5.
Based on the previous explanation, you can conclude that the arithmetic sequence is:
[tex]\begin{gathered} a_n=a_{n-1}+2 \\ a_1=-5 \end{gathered}[/tex]Hence, the answer is option C
