Possible answers are:
a) absorb solar energy
b) absorb carbon dioxide
c) release carbon dioxide
d) are released during the combustion of fossil fuels
Greenhouse gases are gases released during the combustion of fossil fuels, burning fire and decomposition or organic compounds. Example of greenhouse gases are carbon dioxide, water vapour, ozone, methane and nitrous oxides. Their main effect is that they are good at capturing heat and bad at releasing it. This causes raise of temperature accross Earth.
From this explanation we can find that a) and d) are correct answers. Greenhouse gases do not absorb or release carbon dioxide. This is done by plants and animals.