Consider a simple process where work flows from Activity A to Activity B to Activity C to Activity D. Activity A takes 3 minutes and is performed by Aaron. Activity B takes 5 minutes and is performed by Aaron and Betty together. Activity C takes 4 minutes and is performed by Betty and David together. Activity D is performed by David and takes 3 minutes. What is the bottleneck of the process?

 (a) None of these
 (b) Activity B
 (c) Betty
 (d) Aaron
 (e) Activity C