Why Are Curvilinear Relationships Hard to Detect with Correlation Coefficients

Multiple Choice

Why are curvilinear relationships hard to detect with correlation coefficients (r) ?

A) Because curvilinear relationships require a large amount of scores
B) Because curvilinear relationships have small effect sizes
C) Because r looks for the best straight line to fit the data
D) Because r assumes a zero association
E) Because r assumes a negative relationship