I'm going with C. It may be wrong but I think it's C.
They all contain carbonyl groups. DNA has carbonyl groups in it's nucleotide ring structures. Every amino acid in a protein has a carbonyl group in its backbone structure. Fats too have carbonyl groups in their structures attached to hydrocarbon chains
1. Bacteria
2. Grass
3. Earthworm
4. Field Mice
5. Red-tailed hawk