Answer:
(B) calmodulin
Explanation:
Calcium in cells acts as second messenger molecule which regulates the very important physiological and cellular process of cell-like neurotransmission, cell migration, secretion, fertilization and many others.
Calcium acts as a messenger by binding to a calcium-binding protein called calmodulin. Calmodulin forms complex with 4 calcium ions through the side amino acids present in the structure of calmodulin.
Thus, calmodulin is the correct answer.
The crayfish have its nerve cord on the ventral side rather than on the dorsal side. The ventral side is under the Crayfishes' exoskeleton, as opposed to the dorsal side where the exoskeleton is . If it is attacked it will be from the dorsal side and the nerve cord would be snapped easier. The function of the nerve cord is that if it gets attacked by a predator they will go for the top and it will still be able to move.
