What type of correlation coefficient would you use to examine the relationship between the following variables? Explain why you have selected the correlation coefficients.
A. Reading ability (converted to ordinal rank in class) and number of friends in class (converted to ordinal rank).
B. Political party (Democrat or Republican) and rank in high school graduating class.
C. IQ score and subjective well-being score.
D. Gender (male or female) and score on a test of musical-ability.