The correct option is B.
A positive feed back refers to the amplification of a particular effect by its own influence on the process that gives rise to it. In positive feed back, the specific response that is obtained as a result of a process continue to increase as the process continues or increase, that is both the process and the effect generated increase.
In an experiment, that subjected participants to increasing isolation in a computerized ball-tossing game, fMRI scans showed activity in the cingulate cortex, a region of the brain that is active during EMOTIONAL PAIN.
Cingulate cortex is the limbic lobe involved in emotion formation, memory, learning, problem solving and self control.
Both the extremities, flagella and cilia, are alike in that they help the cell in this mobilization. Thus, the answer to this item is letter "C. they assist with movement". With their appearances, both are hair - like structures but flagella are longer compared to the cilia.
