This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Biochemistry
A small Ca+2 binding protein that modifies the activity of many enzymes and other proteins in response to changes of Ca+2 concentration is known as: 
Select and explain. 
A. Cycline, B. Calmodulin, C. Collagen, D. Kinesin
B: Calmodulin
Answer: B: Calmodulin 
Explanation: None