I think the answer is C. Hope it helps
The answer to this question would be: excess fluoride intake
The toothpaste has a high amount of fluoride and will increase the blood fluor level. Excess fluoride intake in children can cause fluorosis which was the brown staining of teeth because fluor is deposited in the growing teeth. Fluorosis can happen in children with <8-year ages.
Eukaryotes that are not fungi, animals, or plants are called protists
Protists can be described as eukaryotes that are not grouped as fungi, animals or plants. These groups of organisms are so wide that there are lots of organisms that fall under this category.
Protists are tiny group of organisms that can only be seen/viewed with the aid of a strong microscope. Protists only have one type of cell and lots of these organisms are found in an aquatic environment.
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Sneezing is an involuntary action because it's something we cannot control.
