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 standard deviation of the critical path? a) greater than 1.0 but less than or equal to 2.0 days O b) less than or equal to 1.0 days O c) greater than 2.0 but less than or equal to 3.0 days O d) greater than 3.0 days