The right option is; hormone
Hormone is a substance that acts at a long distance from the site at which it is secreted.
Hormones are chemical substances and special chemical messengers produced in the endocrine glands to maintain homeostasis, and to control most physiological activities, such as hunger/appetite, reproduction, emotions and mood. When hormone-producing glands such as thymus or pancreas secretes hormones into fluids such as blood, the hormones will travel from the site at which it is secreted until it reach cells that will read the chemical as a message. Types of hormones include; cortisol, estrogen, testosterone, progesterone and melatonin.
