Answer:
the answer would be D. synaptic peptide. The synapse, the firing of an action potential in one neuron—the presynaptic, or sending, neuron—causes the transmission of a signal.
Explanation:
The question being tested is whether or not the human body will produce more red blood cells at higher altitudes.
The hypothesis an athlete would create from this question is that the body will produce more red blood cells at a higher altitude to ensure the pumping of oxygen throughout the body.
I don't get it theres so much symbols
