One advanatage of hormones as messengers verses electrical signals (neurotransmitters) is
a. hormones can persist much longer than electrical signals
b. hormones cannot spread to all of the tissues via the blood as can electrical signals
c. hormones are broken down quickly and do not persist as long as electrical signals
d. there are a specific group of molecules that can only act as a hormone.

a. Hormones can persist much longer than electrical signals

Explanation:

Althought hormonal response is slower than electrical signals it affects a large number of organs and sistems. Example: electrical signals are for the openening or closing channels of sodium/potassium wich causes ionic differences on the cells producing quick reponses like movement or blood pressure changes. Meanwhile hormonal response control larger sistems and more complex process like pregnancy  

the answer to your question is b

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