Chlorofluorocarbons (CFCs) are belived to be associated with cancers because,

Options

A. CFCs react with DNA and cause mutations
B. CFCs react with proteins involved in DNA repair
C. CFCs destroy the ozone layer and permit harmful UV rays to reach the earth
D. CFCs react with DNA polymerase and reduce fidelity of DNA replication

Explanation

To answer the question regarding why chlorofluorocarbons (CFCs) are believed to be associated with cancer, we can analyze the provided options step by step.

### Step-by-Step Solution:

1. **Understanding CFCs**: Chlorofluorocarbons (CFCs) are chemical compounds commonly used in refrigeration, air conditioning, and aerosol propellants. They are known to have harmful effects on the environment, particularly on the ozone layer.

2. **Ozone Layer Function**: The ozone layer, located in the stratosphere, serves as a protective shield for the Earth by absorbing the majority of the sun's harmful ultraviolet (UV) radiation.

3. **Impact of CFCs on Ozone Layer**: When CFCs are released into the atmosphere, they eventually rise to the stratosphere where they release chlorine atoms. These chlorine atoms catalyze the breakdown of ozone (O3) into oxygen (O2), leading to the depletion of the ozone layer.

4. **Consequences of Ozone Depletion**: The depletion of the ozone layer allows increased levels of UV radiation to reach the Earth's surface. This increased exposure to UV rays is known to cause mutations in DNA, which can lead to various forms of cancer, including skin cancer.

5. **Evaluating the Options**:
- **Option A**: CFC reacts with DNA and causes mutation. (Incorrect - CFCs do not directly react with DNA.)
- **Option B**: CFC reacts with proteins involved in DNA repair. (Incorrect - There is no evidence that CFCs interfere with DNA repair proteins.)
- **Option C**: CFC destroys the ozone layer and permits harmful UV rays to reach the earth. (Correct - This is the primary reason for the association with cancer.)
- **Option D**: CFC reacts with DNA polymerase and reduces fidelity of DNA replication. (Incorrect - CFCs do not interact with DNA polymerase in this manner.)

6. **Conclusion**: The correct answer is **Option C**: CFC destroys the ozone layer and permits harmful UV rays to reach the earth, which can lead to mutations in DNA and increase cancer risk.