Consider the project network shown below. Think about fast-tracking in the absence of resource constraints. Suppose activities 5-8 and 8-12 can be done in parallel. At what level of parallelization is the original critical path no longer the only critical path?

Critical Path (ignoring resource availabilities) (3,3) (8,8) (15,15) 5 7 2 5 6 8 3 (0,0) 2 4 (9,11) (11,13) 1 (5,7) 2 (21,21) Original 3 8 6 9 12 3 2 4 2 10 (3,17) (5,19)