Solution
= Solution
The matrix $C$ is antisymmetric, so the scalar <Majorana spinor> bilinear is \b[not identically zero]. For example, choose two independent odd <Grassmann variables> $\lambda_\alpha,\lambda_\beta$ at a pair of indices with $C_{\alpha\beta}\ne0$. Their contribution is $2C_{\alpha\beta}\lambda_\alpha\lambda_\beta$, which is nonzero as a Grassmann polynomial. This is why a <Majorana mass term> is possible.