human
Divide algebraic fractions involving non-linear expressions STEP \( 3 \)

Which of the options is the final answer, expressed as simply as possible?
\(
\begin{aligned}
& \frac{3 x+1}{3} \div \frac{9 x^{2}-1}{12} \\
= & \frac{3 x+1}{3} \times \frac{12}{9 x^{2}-1} \\
= & \frac{3 x+1}{3} \times \frac{12}{(3 x-1)(3 x+1)}
\end{aligned}
\) \( \frac{4(3 x+1)}{(3 x-1)(3 x+1)} \)
gpt
When simplifying an algebraic fraction, only looks for number factors