Which of the following statements are true for all square matrices?
a. A and Aᵀᵀ have the same eigenvalues.
b. If 0 is not an eigenvalue of A, then A is invertible.
c. If A is an n×n matrix with n different eigenvalues, then A is diagonalizable.
d. If A is a real matrix, then A has a real eigenvalue.
e. If A is invertible and λ is an eigenvalue of A, then λ⁻¹ is an eigenvalue of A⁻¹.