Which of the following statements are relevant with respect to Pearson's Product-Moment Correlation coefficient?

A. Both variables have come from the normally distributed population.

B. r_xy is a non-parametric measure of the relationship.

C. It is known as the covariance of the two variables.

D. It is highly suitable to measure relationship of attributes like 'preferences’ 'efficiency’ and intelligence’,

Choose the most appropriate answer from the options given below:  

The correct answer is A and C only .Important Point

A. Both variables have come from the normally distributed population:

• This is true.
• Pearson's correlation assumes that each of the two variables it is comparing are normally distributed.

B. rxy is a non-parametric measure of the relationship:

• This is false.
• Pearson's correlation is a parametric measure.

C. It is known as the covariance of the two variables:

• This is not entirely correct.
• While Pearson's correlation does involve covariance in its calculation (it's the covariance of the two variables divided by the product of their standard deviations), it is not the same as covariance.

D. It is highly suitable to measure relationship of attributes like 'preferences' 'efficiency' and 'intelligence':

• This statement can be misleading.
• While Pearson's correlation can be used to measure the relationship between two variables, the variables need to be interval or ratio measurements and linearly related. 'Preferences', 'efficiency', and 'intelligence' may not always meet these criteria, depending on how they are measured.

So, while this is a bit of a complex question and none of the answers fit perfectly, option 3 (A and C only) is the best fit among the given choices.