The true statement about chromosomes is: Chromosomes contain DNA.
To clarify the other statements:
- DNA does not contain chromosomes; rather, chromosomes are made up of DNA.
- The same number of chromosomes does not appear in haploid and body cells; haploid cells have half the number of chromosomes compared to body (diploid) cells.
- Chromosomes are not found in sets of three; they typically exist in pairs in diploid organisms.