A private university has a small, satellite branch. All information from the main campus flows to the branch through Iris. Iris then distributes the information as necessary to the pertinent parties at the satellite. Any information from the satellite's instructors or students flows through Iris to the main campus. What communication flow model does the university's satellite branch use?

a$.$ Chain pattern

b$.$ Wheel pattern

c$.$ All$-$channel network

d$.$ Backdoor network