For any matrix $A$, the property $(A^T)^T$ equals:
A$A^{-1}$
B$A$
C$-A$
D$A \cdot A$
Answer & Solution
Correct answer: B. $A$
Transposing twice undoes the operation: $(A^T)^T = A$. Intuitively, swapping rows and columns and then swapping them again returns the original matrix.
Other useful transpose rules: $(A + B)^T = A^T + B^T$, $(AB)^T = B^T A^T$ (note the reversal), $(kA)^T = k A^T$ for any scalar $k$.
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