Description 2 describes a commensal symbiosis. The answer is D, commensalism.
Cutoff signals are signals used by the animals for communication between them. These signals are behaviors. Examples are: the animal freezes, turns the back to other animals, moves away, ....
Cut-off signals are usually given after a conflict. One reason animals use cutoff signals is to:
D. encourage compromise between potential adversaries
If cut-off signals are not respected, conflict will escalate.
According to Thelen {1986}, THE STEPPING REFLEX may contribute to the birthing process.
Stepping reflex is one of the reflexes demonstrate by new born babies. When resistance is exerted on the feet of a new born baby, the baby will respond by placing one foot in front of the other, this is called stepping reflex and Thelen suggested that this reflex may help in the birthing process.
Mucous cells is what I think is the answer. hope it helps ;)