Austin and Tiger tested two procedures that teach tolerance for delay in the delivery of reinforcement. One procedure, which they used only for the replacement behavior of "excuse me," was delay fading, with 30 secs, then 40 secs, then 50 secs, and so on unless the rate of aggression was 1/min, at which point the delay was decreased by 20 sec. Using the delay fading alone, what was the maximum amount of delay time they were able to implement before the rate of aggression increased to 1/min (so that they had to stop increasing the delay)?

Group of answer choices:
A) 60 sec (1 min)
B) 30 sec
C) 120 sec (2 min)
D) 90 sec