Cancer causing viruses are called …………………………….. .

Explanation

**Step-by-Step Solution:**

1. **Understanding Cancer:** Cancer is a disease characterized by uncontrolled cell growth. Unlike normal cells, cancerous cells do not exhibit contact inhibition, which means they do not stop dividing when they come into contact with other cells.

2. **Role of Viruses in Cancer:** Certain viruses can lead to the transformation of normal cells into cancerous cells. These viruses can introduce genetic material into the host cells, altering their normal functioning.

3. **Definition of Cancer-Causing Viruses:** The specific viruses that are responsible for causing cancer are known as oncogenic viruses.

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