Genes are segments of DNA, which means that de DNA is composed of a series of genes. The chromosomes are composed of hundreds of thousands of genes. So, the DNA containing the information for the production and function of proteins is arranged in genes. Those genes are arranged in groups of hundreds of thousands, forming a chromosome. Therefore, A) is wrong because genes are related to chromosomes, being parts of it. C) is also wrong, because chromosomes contains genes, not the opposite. D) is incorrect as well because chromosomes often contain hundreds of thousands of genes, not only hundreds. In the end, the correct answer is B), because DNA is indeed made of genes which are located on chromosomes.