Answer is: d. Carbon-based macromolecules are found in all life forms.
Carbon (symbol: C) is the main element in organic compounds, found in living things.
There are approximately 10 million carbon-based compounds in living things, for example proteins (enzymes, antibodies), carbohydrates (sugars), lipids (fats, oils) and nucleic acids (deoxyribonucleic acid DNA, ribonucleic acid RNA).
The reason for so many carbon-based compounds is carbon characteristic to form bonds (single, double, triple) with many different elements.