For Which One of These Relationships Could We Use a Regression

Multiple Choice

For which one of these relationships could we use a regression analysis? Only one choice is correct.

A) Relationship between weight and height.
B) Relationship between political party membership and opinion about abortion.
C) Relationship between gender and whether person has a tattoo.
D) Relationship between eye color (blue, brown, etc.) and hair color (blond, etc.) .