Diagonal terms ($Y_{ii}$) are always the sum of all admittances connected to the node.

Off-diagonal terms ($Y_{ij}$) are the negative of the admittance connected between node $i$ and node $j$.

The matrix $Y_{bus}$ is symmetric if the system contains no phase-shifting transformers.

For a network with $n$ buses, $Y_{bus}$ is an $n \times n$ matrix.

Highly sparse matrix, reducing memory requirements for large power systems.

Used extensively in load flow studies (Newton-Raphson, Gauss-Seidel).

Calculation can become computationally intensive for very large networks if not properly optimized.

Does not account for non-linear characteristics of certain equipment directly without linearization.

Power flow analysis

Short circuit studies (Fault analysis)

Stability studies

Off-diagonal terms in $Y_{bus}$ represent mutual admittance between buses.

Option A is incorrect because mutual admittance corresponds to the off-diagonal terms ($Y_{ij}$ for $i \neq j$).