E none 47. A simple project listing of five activities and their respective time estimates are presented below: Activity Time in Days - 2 Immediate Predecessor None A B and C D D 2 Using CPM, what activity has slack and how much? AB, 1 day B. C. 1 day C. B, 2 days D. C, 2 days E. D, 1 day 48. You have the following time and cost information below for use in a Time-Cost CPM Scheduling model. Activity Normal Time Crash Time Normal Cost $400 $600 $300 Crash Cost $600 $1200 $1500 What are the three costs per unit of time to expedite each activity? A. A=$300, B=$200, C-$300 B. A=$100, B=$200, C-$400 C. A $200, B=$200, C-$200 D. A $100, B-$400, C-$300 E. A=$200, B=$300, C=$400