When Keith Had to Give a Presentation to the Entire

When Keith had to give a presentation to the entire class,his classmate Daniel decided to wear a large fake moustache to make Keith laugh.To Daniel's disappointment,when Keith gave his presentation,he seemed completely unaffected,despite looking at Daniel several times.Afterward,Keith said that he was so focused on the presentation that he didn't even notice the moustache! This scenario is an example of

A) inattentional blindness.
B) a blind spot.
C) top-down processing.
D) sensory adaptation.