Answer:
produces infertile offspring.
Explanation:
<span>a. chemicals produced by neurons that function as hormones—neurohormones
b. chemicals that act locally on nearby cells—paracrine factors
c. chemicals secreted by presynaptic terminal—neurotransmiters
d. influences same cell type from which it is secreted—autocrine agent
e. chemical secreted into the blood by specialized cells; travels some distance to target tissues—endocrine hormones</span>
It's either 3.5 or 1.2
There would be more evidence spread out through space to be noticed by scientists and it seems like a stretch to go as far back as 4 billion years ago.
(I mean really? That much before the DINOSOURS died? I don't think so)
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Hope this helps
Miri
