Question

the chemical substances that are secreted into the bloodstream by the endocrine system are known as
o glands.
o hormones.
o neurotransmitters.
o factors.

Explanation:

The endocrine system secretes chemical substances called hormones into the bloodstream to regulate various bodily functions. Neurotransmitters are used for communication in the nervous - system across synapses, not secreted into the bloodstream by the endocrine system. Factors is a very general term and glands are the structures that secrete hormones, not the secreted substances themselves.

Answer:

C. hormones