The answer is D, moist skin surfaces.
Explanation:
Cnidaria and flatworms respirate and extreme through their skin via diffusion.
<span>Answer: a. overabundance; synaptic connections
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In early childhood, the brain creates overabundance link of the nerve cells called synapses. The link will allow the brain cells have multiple paths to communicate with each other so that if some cells died the path is not blocked. The synaptic connections will be reduced later by a process called pruning.
