A mutation is any change in the sequence of DNA because of any reason such as deletion, insertion, etc. To determine the mutation in a DNA molecule changed the structure of a specific protein scientists should know the normal sequence of bases that code for the protein.
A mutation is a random change in the DNA sequence either due to insertion, deletion, or substitution.
By mutating a gene's code for making a protein, a variant can leads to a protein's improper functioning or to not being produced at all.
Scientists must mandatorily determine the normal base sequence of the protein code before investigating the mutation in the DNA sequence for a particular protein.
Thus, the correct option is A.
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