40 30 20 17. Which of the following is a valid argument? Show the proof using the valid form. [2 Marks] a. All rational numbers are real numbers. 2 is a fraction. Therefore, is a real number. b. All men are polygamous. Jay is a man. Therefore, Jay is not a woman. c. All actors are robots. Tom Cruise is a robot. Therefore, Tom Cruise is a robot. d. All negative integers are less tan zero. -56 is a negative integer. Therefore, -56 is less than zero.