Duplication mutation occurs when the whole nucleotide sequence of a gene or part of it is copied. Hence, a chromosome has more than one copy of a gene or part of it.
The given gene sequence is "ATTCATTCA". In option C, the nucleotides at position 4 and 5 are duplicated. This results in the final gene sequence as "ATTCACATTCA". The duplicated segment is shown by "CACA" in the final gene sequence.
