The correct answer is "<span>a layer of smooth </span><span>muscle".
</span>In an individual's mouth, gut, and the small intestine, the mucosa, which holds tiny glands, which secrete juices in order to assist in digesting food<span>. The </span>digestive<span> tract also holds a layer of smooth </span>muscle, which <span>aids in breaking down </span>food<span> and move it along the digestive tract.</span>
<span>Central nervous system
Sympathetic nervous system
The neuron, a cell that composes the nervous system. For example a brain, an organ composed of thousands of neural fibers and glial cells that performs many important organismic functions. </span>
<span>Neurons are specialised cells that have dendrites, axons and terminal buttons that sends and receives stimuli from the environment and transduces it into a meaningful information and understand the complexities which the brain now functions.<span>
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It is true that rivers and streams are biodiverse ecosystems that are sensitive to change. Details about rivers and streams can be found below.
<h3>What is river and stream?</h3>
A river is a large and often winding stream which drains a land mass, carrying water down from higher areas to a lower point, oftentimes ending in another body of water, such as an ocean or in an inland sea.
On the other hand, a stream is a small river or a body of moving water confined by banks.
Rivers and streams are both freshwater ecosystems, hence, tend to respond to changes in their environment caused by anthropogenic activities.
Therefore, it is true that rivers and streams are biodiverse ecosystems that are sensitive to change.
Learn more about rivers and streams at: brainly.com/question/10904801
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