Loss of Productivity Is Least Likely to Occur in Which

Loss of productivity is least likely to occur in which of the following scenarios?

A) Daphne isn't quite sure what her role in the group is.
B) Fred must play both an instrumental and an expressive role in the group.
C) Velma's role in the group seems to be constantly changing.
D) Shaggy assumes a clearly defined instrumental role in the group.