**Core Concept**
The question is related to the concept of global warming, which refers to the long-term increase in the average temperature of the Earth's surface due to the trapping of heat by greenhouse gases in the atmosphere. This phenomenon is primarily caused by human activities that release large amounts of carbon dioxide and other greenhouse gases.

**Why the Correct Answer is Right**
The correct answer is related to the fact that carbon dioxide (CO2) is the most prevalent greenhouse gas responsible for global warming. CO2 is released through various human activities such as burning fossil fuels, deforestation, and industrial processes. The increased concentration of CO2 in the atmosphere leads to a trapping of heat, resulting in a rise in global temperatures.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because methane (CH4) is another potent greenhouse gas, but it is not the primary contributor to global warming.
**Option B:** This option is incorrect because nitrous oxide (N2O) is also a greenhouse gas, but it has a lower global warming potential compared to CO2.
**Option C:** This option is incorrect because ozone (O3) is a major component of the stratospheric ozone layer, but it is not a primary contributor to global warming.

**Clinical Pearl / High-Yield Fact**
It's essential to note that the concentration of CO2 in the atmosphere has increased by about 40% since the Industrial Revolution, primarily due to human activities. This increase has led to a significant rise in global temperatures, with far-reaching consequences for the environment, ecosystems, and human health.

**Correct Answer: D. Carbon dioxide.**