Fact 1: Endocrine hormones travel throughout the body in the blood.

Fact 2: Hormones are the chemical messengers of the body's endocrine system.

Given the two facts above, answer the question "what travels throughout the body in the blood?" with the following options: 
- chemical messengers
 - carbon monoxide
 - Veins and arteries.
 - bacterial messengers
 - density
 - kinetic energy
 - electromagnetic energy
 - matter vibrating


 

 chemical messengers        