Final answer:
The nucleus is the major structure in the cell that contains genetic material, which is organized into chromosomes consisting of DNA and proteins.
Step-by-step explanation:
The Nucleus and Genetic Material
The major structure within the cell that contains genetic material is the nucleus. The nucleus is often referred to as the control center of the eukaryotic cell because it houses most of the cell's genetic information in the form of DNA. This DNA is organized into structures called chromosomes, which are strands of DNA wrapped around proteins. The nucleus contains one or more nucleoli, which are responsible for synthesizing ribosomes, and is encased by the nuclear envelope with its selective nuclear pores that regulate the exchange of materials between the nucleus and the cytoplasm. Though mitochondria also contain DNA (mitochondrial DNA), it represents only a small percentage of the cell's total genetic content. Therefore, the correct answer to the question is C) Nucleus.