Task: Instance Class Understanding (ontology: Sciences/Computer_Science)

Which of the following classes does 'pT0 (colon)' belong to as one valid explicit type? Context: A pathologic primary tumor stage for colon and rectum according to AJCC 7th edition indicating that there is no evidence of primary tumor.

A. histologic grade for ovarian tumor
B. pathologic distant metastases stage for kidney according to AJCC 7th edition
C. pathologic primary tumor stage for colon and rectum according to AJCC 7th edition
D. pathologic lymph node stage for lung according to AJCC 7th edition

Answer: pathologic primary tumor stage for colon and rectum according to AJCC 7th edition