Excision repair systems replace a short stretch of DNA around the site of damage. The following statements are made about nucleotide excision repair in E. coli:

A. UvrB homodimer creates the nicks on one strand on both sides of the lesion.
B. The 50–60 residue-long stretch of DNA between the two nicks is removed by the action of UvrD.
C. The gap generated is filled in typically by DNA polymerase I.
D. The distortion caused by the lesion is recognized and bound by UvrA–UvrB complex.

Which one of the following options represents the combination of all correct statements?

Correct option is C

Explanation-

Statement A: UvrB homodimer creates the nicks on one strand on both side of the lesion.
Incorrect
UvrC, not UvrB, makes the dual incision (3' and 5' to the lesion). UvrB helps position UvrC after lesion detection. UvrB does not cut the DNA — this is the main flaw in this statement.

Statement B: The 50–60 residue-long stretch of DNA between the two nicks is removed by the action of UvrD.
Incorrect for E. coli
In E. coli, UvrD unwinds and removes a 12–13 nucleotide-long damaged region. A stretch of 50–60 residues is typical of eukaryotic NER, not prokaryotic.

Statement C: The gap generated is filled in typically by DNA polymerase I.
Correct
After UvrD removes the damaged oligonucleotide, DNA polymerase I synthesizes the replacement DNA.
Confirmed in bacterial NER.

Statement D: The distortion caused by the lesion is recognized and bound by UvrA–UvrB complex.
Correct
Initial recognition of DNA distortion is by the UvrA-UvrB complex. UvrA detects the distortion → UvrB binds DNA and helps recruit UvrC.
This is textbook NER initiation in E. coli.

So, the correct answer is option c - C and D only