Question

which gases contribute to the greenhouse effect?
nitrogen and helium
carbon dioxide and methane
carbon dioxide and helium
nitrogen and methane

Explanation:

Greenhouse gases are those that trap heat in the atmosphere. Carbon dioxide ($\text{CO}_2$) and methane ($\text{CH}_4$) are well - known greenhouse gases. Nitrogen and helium are not greenhouse gases. So we analyze each option:

• Option 1: Nitrogen and helium are not greenhouse gases, so this option is incorrect.
• Option 2: Carbon dioxide and methane are both greenhouse gases, so this option is correct.
• Option 3: Helium is not a greenhouse gas, so this option is incorrect.
• Option 4: Nitrogen is not a greenhouse gas, so this option is incorrect.

Answer:

B. carbon dioxide and methane (assuming the second option is labeled B, if the original options had labels like A, B, C, D with the second option being B. If the original options had different labels, adjust accordingly. But based on the content, the correct option is the one with carbon dioxide and methane)