Single-base substitutions are not always a problem because they

Answer and Explanation:

Single-base substitutions, also called point mutations, happen when only ONE base is altered and replaced by another base. Although this WILL generate a mutated DNA and, consequently, a mutated mRNA sequence, the protein resulting from this gene may not be altered at all. Why? Because proteins are made from 20 different amino acids, but each amino acid can be coded by several codons (a codon is a sequence of three nucleotides). This means that if a base is substituted, the "altered codon" may still code for the same amino acid! If this happens, the protein will be just like any other unmutated protein, and this will be called a "silent mutation".

chert is a sedimentary rock composed of microcrystalline or cryptocrystalline silica. with this little bit of information, you can come to the conclusion that your answer is c.  

explanation:

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