Correct option is D
Explanation-
Option a — "The virus which caused them"
Some viruses can cause cancer (e.g., HPV can cause cervical cancer). But most tumors are not caused by viruses, and this is not the standard way to classify tumors.
So, this is incorrect.
Option b — "The person who discovered them"
Some tumors are named after people (like Hodgkin lymphoma), but we do not classify all tumors this way.
So, this is incorrect.
Option c — "Their metastatic ability"
Metastasis means the ability of cancer to spread in the body. This is used to stage or grade a tumor (how dangerous it is), but not for classification.
So, this is incorrect.
Option d — "The tissue or cell of origin"
This is the correct and standard method. Tumors are grouped by where they begin in the body:
For example:
1. Carcinomas arise from epithelial tissue.
2. Sarcomas arise from connective tissue (bone, muscle, etc.).
3. Lymphomas and leukemias arise from lymphoid or hematopoietic cells.
This helps doctors diagnose, treat, and research cancer types better.
So, the correct answer is option d - The tissue or cell of origin.
