$$\left|\begin{array}{ccc} -2a & a+b & a+c \\ b+a & -2b & b+c \\ c+a & b+c & -2c \end{array}\right| = \alpha(a+b)(b+c)(c+a) \neq 0$$ then $\alpha$ is equal to\\ (1) $a+b+c$\\ (2) $abc$\\ (3) 4\\ (4) 1