Query On PRAGMA-RESTRICT-REFERENCE?

CREATE OR REPLACE FUNCTION CALC_PLAYER_AVG
(V_ID in PLAYER_BAT_STAT. PLAYER_ID%TYPE)
RETURN NUMBER
IS
V_AVG NUMBER;

[code]...

This function must be moved to a package. Which additional statement must be added to the function to allow you to continue using the function in the group by the clause of a select statement?

A. PRAGMA RESTRICT_REFERENCES (CALC_PLAYER_AVG, WNDS, WNPS);
B. PRAGMA RESTRICT_REFERENCES (CALC_PLAYER_AVG, WNPS);
C. PRAGMA RESTRICT_REFERENCES (CALC_PLAYER_AVG, RNPS, WNPS);
D. PRAGMA RESTRICT_REFERENCES (CALC_PLAYER_AVG, ALLOW_GROUP_BY);
Answer: A

----I had gone through this question in dumps,about PRAGMA_RESTRICT_REFERENCES, but i m not aware of WNDS, WNPS..or reference for this term, & how it works in above exampl