Idempotent Matrix: $AA=A^2=A$
Symmetric Matrix: $A=A^T$
Orthogonal Matrix: $AA^T = I$ (Option C)
A Hermitian matrix (or self-adjoint matrix) is a complex square matrix that is equal to its own conjugate transpose.
Bonus:-
Singular Matrix: Matrix whose determinant is 0. It's opposite to Invertible matrix, whose determinant is $\neq$ 0
Skew Symmetric Matrix: $A^T=-A$