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

Which of the following classes does 'G1 (WHO)' belong to as one valid explicit type? Context: A histologic grade for ovarian tumor according to the World Health Organization indicating that the tumor is well differentiated.

A. clinical tumor stage group according to AJCC 7th edition
B. histologic grade for ovarian tumor according to the World Health Organization
C. pathologic primary tumor stage for kidney according to AJCC 7th edition
D. pathologic lymph node stage for colon and rectum according to AJCC 7th edition

Answer: histologic grade for ovarian tumor according to the World Health Organization