The answer is glycogen.
Starch is the form in plants. Plants produces glucose too, but their storage form is starch.
Glucagon and insulin is not correct too. They're the substances produced by pancreas which can maintain a suitable concentration of glucose in blood. They're not the storage form of glucose in human.
Instead, glycogen is the correct answer. Extra Glucose not required is converted into glycogen in the liver which will be stored in the body.
