Given A is a square matrix of order four, B is a 4x3 matrix, C is a 3x2 matrix and D is a 4x4 diagonal matrix whereby D = d | with d; =312 -5j. (a) Construct the matrix D. (b) Determine whether the matrix expressions of AD , DB , BD , (AD)C and (DB)C is defined or undefined. Give the order of the resulting matrix, if it is defined. (c) Determine whether the matrix expression of B+ C is defined or undefined. State your reason