Answer:
3rd option
Step-by-step explanation:
the explicit formula for a geometric sequence is
[tex]a_{n}[/tex] = a₁ [tex](r)^{n-1}[/tex]
where a₁ is the first term and r the common ratio
here a₁ = - 4 and r = [tex]\frac{a_{2} }{a_{1} }[/tex] = [tex]\frac{12}{-4}[/tex] = - 3 , then
[tex]a_{n}[/tex] = - 4 [tex](-3)^{n-1}[/tex]
