Look at the DNA sequence (1st Picture) Which sequence shows a substitution mutation? (2nd Picture) Also, can you explain how you got the correct answer?

Sequence A

CGTTACTGCAAT to CGTGACTGCAAT

Explanation:

Mutation refers to any change, whether big or small, that occurs in the nucleotide sequence of a DNA/gene. This change can either be caused by replicational errors or induced by mutagens. Mutation can be of different types depending on the effects on the affected organism (mutant).

A substitution mutation is a kind of mutation in which one or more nucleotide base is replaced by another in a sequence. This is the case here as the

original sequence: CGTTACTGCAAT

Mutated sequence: CGTGACTGCAAT

The fourth base, T has been replaced by G in the upper strand of the DNA sequence.

the organisms are not adapted to live in some communities or habitats.