**Why does the lack of glucose 6-phosphatase activity in the brain and muscle make good physiological sense?**- Glucose 6-phosphatase allows cells to trap glucose in the cell; however, these tissues primarily rely on noncarbohydrate energy sources.- Glucose 6-phosphatase allows cells to generate glucose through gluconeogenesis; however, gluconeogenesis only takes place in the liver.- Glucose 6-phosphatase allows cells to release glucose into the blood; however, these tissues should never release glucose.- Glucose 6-phosphatase provides glucose 6-phosphate for glycogen synthesis; however, these tissues do not need glycogen.

Carbohydrates are important source of energy and provide nutrients to your body's organs, The mammalian brain depends on glucose as its main source of energy.The glucose molecules obtained from the blood and released from glycogen are necessary to sustain muscle contraction.Muscles get their glucose from the bloodstream; glucose entering mainly by means of the GLUT4 transporter. In the muscle, once it takes glucose out of the blood, it is phosphorylated by hexokinase thus maintaining monomeric glucose in a phosphorylated form. The transporter does not recognize the phosphorylated form and therefore the glucose is retained in the cell. A similar phenomenon occurs in brain cells. In contratsthe liver is concerned with the metabolic state of the body and is involved in glucose homeostasis. Unlike other tissues, it does not store glucose, but takes glucose out of the blood when levels are high, and releases glucose into the blood when levels are low. Glucose-6-phosphatase is an enzyme that catalyzes the hydrolysis of glucose-6-phosphate, resulting in release of a phosphate group and free glucose. This enzyme is therefore necessary for exporting glucose out of the tissue and into the bloodstream. Hence glucose-6-phosphatase allows cells to release glucose into blood and the muscle and brain tissues should not allow the release of glucose. Therefore Option C is the correct option and Options A,B and D are incorrect. Option C is the correct option