Why Did Research Participants in Sperling's Experiment Recall So Few

Multiple Choice

Why did research participants in Sperling's experiment recall so few letters stored in iconic memory?

A) They stopped paying attention after a few stimuli.
B) Proactive interference reduced the effectiveness of recall.
C) The stress of participating in this research became excessive.
D) The remaining stimuli quickly faded from iconic memory.
E) Because participants were not able to recall more than 1 or 2 of the letters during each trial.