we see that
[tex]\begin{gathered} \frac{-12}{4}=-3 \\ \frac{36}{-12}=-3 \\ \frac{-108}{36}=-3 \end{gathered}[/tex]
Then, we have a geometric sequence, and each time we need to muliply by -3 starting from 4, so the closed-form is
[tex]t(n)=4(-3)^{n-1}[/tex]
so, the answer is the second one.
