Which fat-soluble vitamin appears to operate as a coenzyme that modifies proteins to bind with calcium?

Vitamin K

Coenzymes are small, nonproteinaceous molecules that work with an enzyme to initiate the function of an enzyme. They cannot function on their own and require the presence of an enzyme.  An example is vitamin K, a fat-soluble vitamin that modifies protein to bind with calcium. 

b, acidosis

acidosis is when the human body attempts to return the bloods ph levels back to normal when the blood is acidic

i think the answer would be d