Which of the Following Is the BEST Example of Canalization

Which of the following is the BEST example of canalization?

A) Jon and Jerry, MZ twins reared in highly different environments, have different temperaments as adults.
B) Terry and May, who both have brown eyes, are the biological parents of Jessica, who has brilliant blue eyes.
C) Regardless of when they are born, all human infants smile at exactly forty weeks after their conception.
D) Keith, an XYY male, is tall for his age, of average intelligence, and currently having behavioral problems in school.