What are the main ions and their functions in living organisms?

I- Sodium and potassium are widely distributed in organisms and are intimately related in their functions.
II- Calcium is essential for regulating physiological functions such as neuromuscular irritability, cardiac automatism, muscle contraction, and blood clotting.
III- Magnesium is mainly an intracellular cation that participates in more than 300 enzymatic reactions related to energy and protein metabolism.
IV- Iron is an essential mineral for energy and oxidative metabolism, and is necessary for the normal functioning of the body's defense mechanisms.
V- Zinc is essential for the activity of more than 70 enzymes, and is related to energy utilization, protein synthesis, and oxidative protection.
VI- Copper is part of different enzymes that participate in oxidative reactions related to iron metabolism and precursor amino acids of neurotransmitters.
a) Only I, II and III are correct.
b) Only II, III and IV are correct.
c) Only III, IV and V are correct.
d) Only IV, V and VI are correct.
e) All statements are correct.