The true statement about chromosomes is: Chromosomes contain DNA.
Haploid cells (like sperm and egg cells) have half the number of chromosomes compared to diploid body cells (somatic cells), so the first statement is false. The statement "DNA contains chromosomes" is also misleading because chromosomes are made of DNA, not the other way around. Lastly, chromosomes are not found in sets of three; they are found in pairs (diploid) or as single sets (haploid).