A. They impede fish migration and spawning
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Here is a image. Hope this helps :)
Yearly dental visits are a part of good dental hygiene because the dentist will check for cavities, fix them, clean your teeth very thoroughly (or whitening treatment), and check the progress and movement of your teeth. They can also recommend when dental surgery is necessary, for instance, if you have extra teeth that can be removed or when your wisdom teeth are coming in. Hope this helps! :)
Answer:
your question is clearly viewing in my mobile sorry