Annabelle drops a flat metal disk into a slot and then pulls a lever. After repeating this process three times, several flat metals disks fall out of the machine. Annabelle repeats the behavior 5 times and receives more metal disks after the 5th try. On her very next behavior, Annabelle again receives more metal disks. She walks away excitedly, at which point Clarice, who has been watching, immediately hurries to put her own metal disk into the slot so that she can pull the lever. What schedule is occurring in this example? A. none of these are happening
B. Fixed ratio
C. Random interval
D. Fixed interval
E. Random ratio