Which one one of the following acts to increase the release of Ca2+ from endoplasmic reticulum:

A i.e. Inositol triphosphate Inositol triphosphate diffuses to the endoplasmic reticulum, where it triggers the release of calcium into cytoplasm. Inositol triphosphate and diacylglycerol (DAG) both of which are second messengers, are associated with Gq subset of G protein mediated receptors.