Which of the following defines an identity matrix of order n?

Which of the following defines an identity matrix of order n?

• A. A diagonal matrix where all diagonal elements are 0
• B. A scalar matrix with non-zero diagonal elements
• C. A diagonal matrix where all diagonal elements are 1
• D. A square matrix with all elements as 1

Answer: C) A diagonal matrix where all diagonal elements are 1

Explanation: An identity matrix is a diagonal matrix in which every principal diagonal element is exactly 1.