A substitution mutation involves a change in one or more nucleotides in the DNA sequence.
Let's analyze the options given.
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C G T G A C T G C A A T G C A C T G A C G T T A
(The first sequence changes from T to G at the 3rd position, and the second sequence changes from A to C at the 3rd position.) -
C G T A C T G C A A T G C A T G A C G T T A
(The first sequence changes from T to A at the 3rd position, and the second sequence changes from A to T at the 3rd position.) -
C G T T A C T G C A A T G C A A T G A C G T T A
(No changes; it's the same as the original.) -
C G T C T A C T G C A A T G C A G A T G A C G T T A
(The first sequence changes from T to C at the 3rd position, and the second sequence changes from A to G at the 3rd position.)
From the analysis, the sequences that reflect a substitution mutation are the first, second, and fourth options. However, the question seems to imply looking for a distinct substitution from the original sequence.
Option 2 clearly shows a substitution at the first position of the second sequence: T to A.
Therefore, the correct answer showcasing a substitution mutation is: C G T A C T G C A A T G C A T G A C G T T A