The Matrix Below Describes What Kind of Covariance Structure in a Multilevel

Multiple Choice

The matrix below describes what kind of covariance structure in a multilevel model?
$\left( \begin{array} { c c c c } \sigma _ { 1 } ^ { 2 } & \sigma _ { 21 } & \sigma _ { 31 } & \sigma _ { 41 } \\\sigma _ { 21 } & \sigma _ { 2 } ^ { 2 } & \sigma _ { 32 } & \sigma _ { 42 } \\\sigma _ { 31 } & \sigma _ { 32 } & \sigma _ { 3 } ^ { 2 } & \sigma _ { 43 } \\\sigma _ { 41 } & \sigma _ { 42 } & \sigma _ { 43 } & \sigma _ { 4 } ^ { 2 }\end{array} \right)$

A) Variance components
B) Diagonal
C) Unstructured
D) AR(1)