If $\large\frac{T_2}{T_3}$ in the expansion of $(a+b)^n$ and $\large\frac{T_3}{T_4}$ in the expansion of $(a+b)^{n+3}$ are equal, then $n=?$

Question

$\begin{array}{1 1} 3 \\ 4 \\ 5 \\ 6 \end{array}$