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?
$\left( \begin{array} { c c c c } 1 & \rho & \rho ^ { 2 } & \rho ^ { 3 } \\\rho & 1 & \rho & \rho ^ { 2 } \\\rho ^ { 2 } & \rho & 1 & \rho \\\rho ^ { 3 } & \rho ^ { 2 } & \rho & 1\end{array} \right)$

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