0 3 6 -4 Compute each matrix sum or product if it is defined. If an expression is undefined, explain why. Let A = B = 4 5 4 2 3 4 D = - 3A, B - 3A, AC, CD Compute the matrix product - 3A. Select the correct choice below and, if necessary, fill in the answer box within your choice. - 3A= O A. (Simplify your answer.) O B. The expression - 3A is undefined because matrices cannot be multiplied by numbers. O c. The expression - 3A is undefined because A is not a square matrix. O D. The expression - 3A is undefined because matrices cannot have negative coefficients. Compute the martrix sum B - 3A. Select the correct choice below and, if necessary, fill in the answer box within your choice. O A. B - 3A = (Simplify your answer.) O B. The expression B - 3A is undefined because B and A have different sizes. O C. The expression B - 3A is undefined because B and - 3A have different sizes. O D. The expression B - 3A is undefined because A is not a square matrix.Compute the matrix product AC. Select the correct choice below and, if necessary, fill in the answer box within your choice. AC = O A. (Simplify your answer.) B. The expression AC is undefined because the number of rows in A is not equal to the number of columns in C. O C. The expression AC is undefined because the number of columns in A is not equal to the number of rows in C. O D. The expression AC is undefined because the number of rows in A is not equal to the number of rows in C. Compute the matrix product CD. Select the correct choice below and, if necessary, fill in the answer box within your choice. CD = O A. (Simplify your answer.) O B. The expression CD is undefined because matrices with negative entries cannot be multiplied. O c. The expression CD is undefined because square matrices cannot be multiplied. O D. The expression CD is undefined because the corresponding entries in C and D are not equal