The answer to this question would be: <span>B. Receptor site
The receptor site of a neurotransmitter often only receives a specific kind of transmitter. That was because the receptor has a unique 3D structure, so different transmitter wouldn't fit into the receptor. That was similar to lock and key principles.</span>
No... Down Syndrome is a chromosome deficiency that happens during conception when a spem and egg fertilize. Sometimes the X and Y Chromosomes don't add up correctly and can (sadly) cause this deficiency. Water in the mother's lungs can cause pneumonia which can potentially harm the fetus due to lack of oxygen. But this cannot cause down Syndrome. Water in the baby's lungs will also not cause Down Syndrome.
Can you provide more info
