Considering the Number of Possible Linear Prediction Rules for Predicting

Multiple Choice

Considering the number of possible linear prediction rules for predicting Y from X,for any particular set of scores,

A) all rules are equally valid,and it does not matter which one is used.
B) there is one best rule for positive predictions and one best rule for negative predictions.
C) there is one best rule for predicting low scores and one best rule for predicting high scores.
D) there is only one best rule.