Let A be a matrix with the following size A 4 x 3 If defined determine the size of the matrix 3A If an answer is undefined enter UNDEFINED X If not defined explain why O 3A is defined O 3A is not defined because the number of columns of A does not equal the number of rows of A O 3A is not defined because the number of columns of A equals 3 O 3A is not defined because the number of rows of A does not equal 3 O 3A is not defined because 3 is not a matrix