Mr. Sierras' class wants to develop a new smart classroom using Program Evaluation and Review Technique (PERT). The objective is to be the first to design and market the most innovative smart classroom so as to capture the first mover advantage in the U.S. education market. Mr. Sierras' brilliant students have determined the following activities, precedence relationships, and time estimates in days for the project: Activity Immediate Predecessors Optimistic Time Most Likely Time Pessimistic Time a none 4. 6 7 b a 1 2 3 5 5 5 d b 7 9 12 e b 2 4 8 f C, d 6 9 10 what is the expected duration of the critical path? O a) less than or equal to 20 days O b) greater than 25 but less than or equal to 30 days b c) greater than 20 but less than or equal to 25 days O d) greater than 30 days