Because of the lack of nuclei and organelles, mature red blood cells do not contain DNA and cannot synthesize any RNA, and consequently cannot divide and have limited repair capabilities. The inability to carry out protein synthesis means that no virus can evolve to target mammalian red blood cell. Are you clear?

Explanation:
DNA, or deoxyribonucleic acid, is the genetic material found in almost all living organisms. It contains the instructions for the development and functioning of an organism. However, there are certain cells or structures in the human body that do not contain DNA. Let's discuss each option in detail:

Hair root:
- The hair root is the part of the hair follicle that is embedded in the skin.
- It contains various structures such as the dermal papilla, hair matrix, and hair bulb.
- The hair bulb is the actively growing part of the hair and contains cells with active DNA replication.
- Therefore, the hair root does contain DNA.

An enucleated ovum:
- An enucleated ovum refers to an egg cell that has had its nucleus removed.
- The nucleus of the egg cell contains the DNA.
- Without the nucleus, the egg cell does not have DNA.
- Therefore, an enucleated ovum does not contain DNA.

A mature spermatozoan:
- The spermatozoa, or sperm cells, are the male reproductive cells.
- They are produced in the testes through a process called spermatogenesis.
- During spermatogenesis, the sperm cells undergo DNA replication and reduction division to form mature spermatozoa.
- Therefore, mature spermatozoa do contain DNA.

Mature RBCs:
- Red blood cells, or RBCs, are responsible for transporting oxygen throughout the body.
- They are produced in the bone marrow and go through a maturation process that involves the loss of their nucleus.
- Mature RBCs lack a nucleus and other organelles to make more space for oxygen-carrying hemoglobin.
- Since the nucleus is the part of the cell that contains DNA, mature RBCs do not contain DNA.

In conclusion, the correct answer is option 'D' - Mature RBCs do not contain DNA. While the hair root, mature spermatozoa, and an enucleated ovum do contain DNA, the absence of a nucleus in mature RBCs means they do not have DNA.