In the Code Below, Which of the Following Is the Parameter

In the code below, which of the following is the parameter variable?
CREATE OR REPLACE FUNCTION fct_test1_sf (p_num IN NUMBER)
RETURN NUMBER
IS
BEGIN
UPDATE bb_test1
SET col1 = p_num;
RETURN p_num;
END;

A) bb_test1
B) col1
C) p_num
D) fct_test1_sf