Answer:
The above statement is false.
Step-by-step explanation:
When a single nucleotide is changed at a particular position of the nucleotide sequence, then this change will result in the formation of a faulty protein.
This is because that particular position of the genetic sequence is associated with the formation of a particular protein. All the other proteins formed will be normal.
Hence, we cannot attribute all existing changes between the cichlid and coelacanth/frog on this single nucleotide change.
However, if instead of replacement of a T with a C, an addition or deletion had been made, then the entire genetic code would have been altered. This would have resulted in more number of faulty proteins being formed.