If the matrix $A=\begin{bmatrix} 3 & 7 & a\\b & 1 & 5\\-2 & c & 11\end{bmatrix}$ is a symmetric matrix, then the values of a, b and c are :

$a=-2, b=7,c=5$

The correct answer is Option (3) → $a=-2, b=7,c=5$

$A^T=A$ [Symmetric]

$\begin{bmatrix} 3 & b & -2\\7 & 1 & c\\a & 5 & 11\end{bmatrix}=\begin{bmatrix} 3 & 7 & a\\b & 1 & 5\\-2 & c & 11\end{bmatrix}$

$b=7,a=-2,c=5$