Step 1: Understanding the Concept:
The greenhouse effect is the natural process by which specific gases in a planet's atmosphere trap heat, keeping the planet warmer than it would otherwise be.
Step 2: Key Formula or Approach:
The approach is to identify which of the listed atmospheric gases absorbs and emits radiant energy within the thermal infrared range.
Step 3: Detailed Explanation:
Greenhouse gases allow sunlight to pass through the atmosphere but prevent the heat that the sunlight brings from leaving the atmosphere.
Carbon dioxide \( (\text{CO}_2) \) is the primary greenhouse gas emitted through human activities and is the main driver of the enhanced greenhouse effect.
Oxygen and Nitrogen make up the vast majority of Earth's atmosphere, but they are transparent to infrared radiation and therefore do not act as greenhouse gases.
Hydrogen is a trace gas and is not a significant contributor to the greenhouse effect on Earth.
Step 4: Final Answer:
Thus, Carbon dioxide is primarily responsible for the greenhouse effect among the given options.