In Which of the Following Situations Would Social Loafing Most

In which of the following situations would social loafing most likely be observed?

A) In a small group.
B) In a group in which the contributions of each person are combined together so that we cannot tell who contributed what.
C) In a group in which the task is seen as important to the group members.
D) In a group in which everyone is working on the same task, and thus the quality of the individual work can be compared.