Which of the following is not responsible for causing global warming?  A. Ozone layer  B. Jet planes  C. Methane  D. Carbon dioxide

To determine which option is not responsible for causing global warming, we need to understand the roles of each listed factor.

1. Ozone Layer: The ozone layer is primarily located in the stratosphere and absorbs the majority of the sun's harmful ultraviolet radiation. While depletion of the ozone layer can have environmental consequences, it does not directly contribute to global warming in the same way that greenhouse gases do.

2. Jet Planes: Jet planes emit carbon dioxide and other greenhouse gases directly into the atmosphere, contributing to global warming.

3. Methane: Methane is a potent greenhouse gas that significantly contributes to global warming, much more so than carbon dioxide over a short time frame.

4. Carbon Dioxide: Carbon dioxide is one of the primary greenhouse gases responsible for global warming, released through burning fossil fuels, deforestation, and various industrial processes.

Final Conclusion

Given the analysis, the correct answer is A. Ozone layer, as it does not directly cause global warming like the others.