The endocrine system releases hormones that travel to their target organs througha)the circulatory systemb)the respiratory systemc)the excretory systemd)the digestive system

Circulatory system

Explanation:

The endocrine system releases hormones in the the circulatory system of the body. The endocrine system can be defined as the chemical substances that is used to generate various responses of the body.

The endocrine system of the body functions to control the reproductive system of the body, hormones that regulates the functions of the brain et cetera.

The hormones released from the glands are transported via the circulatory system of the body.

i think it is true in my reasonment ..

an active site is a region that is present on an enzyme where the reactants or the substrate molecules we can say bind and experience a chemical reaction. the substrate is basically a reactant whose concentration is changing and that is converting into a product after binding at the active site of an enzyme