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
Which of the following substances acts to increase the release of Ca++ from endoplasmic reticulum? 
Select and explain. 
A. Inositol triphosphate, B. Parathyroid hormone, C. 1,25-dihydroxy cholecalciferol, D. Diacylglycerol
A: Inositol triphosphate
Answer: A: Inositol triphosphate 
Explanation: In a large number of tissues, calcium is released as a consequence of the hydrolysis of phosphatidyl inositol. The inositol 1,4,5 triphosphate (InsP3) formed is able to release calcium from internal stores. Ref: Skeletal Muscle in Health and Disease: A Textbook of Muscle Physiology, David A. Jones, Joan M. Round - 1990, Page 49 ; Elements of Molecular Neurobiology By Christopher Upham Murray Smith 2002, Page 231