Hey There!
Mutations:
Mutations are the changes produced in the nucleotide sequence of the genome.
There are four main types of mutations
Substitution
Insertion
Deletion
Duplication.
DELETION:
A small segment of chromosome mat be missing. This condition is known as deletion.
For example, Normal chromosome has A B C D E F G. If deletion mutation occurs then mutated chromosome has A D E F G and B C got deleted.
DUPLICATION:
In this condition, a part of chromosome present in exec ess to the normal chromosome.
For example, Normal Chromosome has A B C D E F G. If duplication mutation occurs, then mutated chromosome had A B C B C D E F G and B C is duplicated.
SUBSTITUTION MUTATION:
Substitution is a type of mutation where one base pair is replaced by a different base pair.
For example, in the sequence CAAGT, if C replaces G, it is a substitution mutation.
INSERTION MUTATION:
In genetics, an insertion is the addition of one or more nucleotide base pairs into a DNA sequence.
For example, in the sequence CAAGT, if extra base G gets inserted after C, the new sequence would be CGAAGT.
Both substitution and insertion mutations change the position of nucleotide thus, the type of amino acid. Option A is correct because B and D are wrong as increase in number of bases and decrease in number of bases is because of deletion and duplication mutations here it asks for substitution and insertion mutations. C is wrong as In mutation there is always a change in bases or chromosome. So all the other choices seem incorrect as it is asking for substitution and insertion the base pair changes which results in the change in type of amino acid.
Best Regards,