Answer:
Option C. T-group.
A T-group or a sensitivity-training group is when participants (normally 8 to 15 people) work towards a specific goal while learning about themselves and others in the process.
They get to deeply know each other and help each other, each step of the way.
An example of a well-known T-Group is something like Alcoholics Anonymous. A group who gather to help each other to overcome an addiction, while they closely interact with their companions, and gain a better insight of those around them.