Which of the Following Would Be the Best Example of the Ergonomic

Which of the following would be the best example of the ergonomic principle of compatibility?

A) Two people are more likely to fall in love if they share many common interests.
B) A drug that produces a mild effect, produces a stronger effect when combined with a second drug.
C) A knob that is turned clockwise moves a machine to the right; the machine moves to the left when the knob is turned counterclockwise.
D) People who are good at learning one task will probably be good at learning another one also.