The true statement about chromosomes is:
Chromosomes contain DNA.
This statement is correct because chromosomes are structures made of DNA and proteins that carry genetic information. The other statements are not accurate. Chromosomes are typically found in pairs (diploid) or single sets (haploid), and haploid and body cells (diploid) do not have the same number of chromosomes. Additionally, while DNA is found in chromosomes, chromosomes do not contain DNA; rather, they are made of DNA.