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?
$\left( \begin{array} { c c c c } \sigma _ { 1 } ^ { 2 } & 0 & 0 & 0 \\0 & \sigma _ { 2 } ^ { 2 } & 0 & 0 \\0 & 0 & \sigma _ { 3 } ^ { 2 } & 0 \\0 & 0 & 0 & \sigma _ { 4 } ^ { 2 }\end{array} \right)$

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