The correct option is B CO2
When the solar radiation falls on earth surface heating it, a small proportion is reflected back. Earth's surface re-emits heat in the form of infrared radiation but part of this does not escape into space as atmospheric gases (e.g., carbon dioxide, methane, etc.) absorb a major fraction of it is called as greenhouse effects. The molecules of these gases absorb solar energy and increase the earth's temperature and these gases are called as greenhouse gases. Thus, the correct answer is option B.