Which of the following is associated with cancer?
I. Oncogene
II. Proto-oncogenes
III. Loss of contact inhibition
IV. Cell differentiation

Options

A. I and II
B. I and III
C. II and IV
D. III and IV

Answer

To determine which of the following options are associated with cancer, we will analyze each option step by step.

### Step-by-Step Solution:

1. **Oncogene (I)**:
- Oncogenes are mutated forms of genes that normally help cells grow. When these genes are mutated or expressed at high levels, they can lead to uncontrolled cell division and cancer. Therefore, oncogenes are directly associated with cancer.
- **Conclusion**: Oncogenes are associated with cancer.

2. **Proto-oncogenes (II)**:
- Proto-oncogenes are normal genes that play a role in cell growth and division. They can become oncogenes through mutations or increased expression. However, in their normal state, proto-oncogenes are not directly associated with cancer. They are essential for normal cellular functions.
- **Conclusion**: Proto-oncogenes are not directly associated with cancer.

3. **Loss of contact inhibition (III)**:
- Contact inhibition is a process that stops cells from dividing when they come into contact with each other. In cancer cells, this mechanism is often lost, leading to uncontrolled growth and proliferation. Therefore, loss of contact inhibition is a characteristic of cancer cells.
- **Conclusion**: Loss of contact inhibition is associated with cancer.

4. **Cell differentiation (IV)**:
- Cell differentiation is the process by which a less specialized cell becomes a more specialized cell type. In cancer, cells often lose their differentiated characteristics and revert to a more primitive state, which is not the same as the process of differentiation. Thus, while differentiation is a normal cellular process, its loss is not directly associated with cancer.
- **Conclusion**: Cell differentiation is not directly associated with cancer.

### Final Assessment:
Based on the analysis:
- **I. Oncogene**: Associated with cancer (Correct)
- **II. Proto-oncogenes**: Not associated with cancer (Incorrect)
- **III. Loss of contact inhibition**: Associated with cancer (Correct)
- **IV. Cell differentiation**: Not associated with cancer (Incorrect)

### Correct Answer:
The options associated with cancer are I (Oncogene) and III (Loss of contact inhibition).

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