Increasing the stimulation up to the maximal stimulus
B, burrowing action of earthworm
The correct option is D.
If water density at freezing point is greater, the ice formed will sink to the bottom of the water body and freeze the water up from the bottom. This will surely lead to the death of everything that live inside the water.
A signal cascade is a series of chemical reactions which are triggered by a stimulus acting on a receptor that is then transduced to the intracellular space through second messengers. Finally, effector molecules receive the signal causing a cellular reaction to the initial stimulus. A signal cascade is very useful because it facilitates and accelerates the communication between cells that could be in different parts of a living organism. This communication is vital for cell processes in complex multicellular organisms.
