Which one is a valid covariance matrix a 0.1 0.3 0.1 a. 0.3 0.2 -0.2 -0.1 -0.2 0.3 b. .1 0.3 0.1 0.3 -0.2 -0.2 L0.1 -0.2 0.3 - 0010 C. 10.1 0 0.2 0 0 0 0 0.3. 0 d. 0.1 0.3 0.1 0 0.2 -0.2 0 0 0 0.3 . e. None of the above is a valid covariance matrix