Answer: A
Z12.11 is the correct code for this case because it is used to code for an encounter for screening for malignant neoplasm of the colon which is done in this patient using colonoscopy.
Option B is not correct because Z11.1 is used to code for an encounter for screening for respiratory tuberculosis.
Option C is not correct because Z08 is used to code for an encounter for a follow-up examination that is done after completed treatment for malignant neoplasm which is not done in this patient.
Option D is not correct because Z09 is used to code for encounters for follow-up examination that is done after completed treatment for conditions other than malignant neoplasm which is not done in this patient.