The Primacy Effect in a Serial Position Curve Can Be

The primacy effect in a serial position curve can be eliminated if

A) subjects rehearse all words equally often, suggesting that the primacy effect is caused by retrieval from STM.
B) subjects rehearse all words equally often, suggesting that the primacy effect is caused by retrieval from LTM.
C) subjects perform another task for 30 seconds, suggesting that the primacy effect is caused by retrieval from STM.
D) subjects perform another task for 30 seconds, suggesting that the primacy effect is caused by retrieval from LTM.