(1) The first operand in each case except for 12 is odd, so 12×5 could be considered the odd one out.
(2) The second operand in each case except for 8 is odd, so 9×8 could be considered the odd one out.
(3) The second operand in each case except for 8 is a prime number, so 9×8 could be considered the odd one out.
(4) The first operand in each case except for 12 is a perfect square, so 12×5 could be considered the odd one out.