Final answer:
All the given options A. Circular DNA, B. Linear DNA, C. RNA, and D. Segmented DNA have been observed in various types of viral chromosomes, therefore, none of the options provided has not been observed as a chromosome of viruses.
Step-by-step explanation:
The chromosome types observed in viruses include circular DNA, linear DNA, RNA, and segmented DNA. All of these forms of genetic material have been found in various types of viruses. For instance:
- Circular DNA is observed in some bacteriophages, which infect bacteria.
- Linear DNA is found in viruses like adenoviruses.
- RNA, which can be either single-stranded or double-stranded, is present in RNA viruses like the flu or HIV.
- Segmented DNA, where the genome is divided into several pieces, is seen in viruses like the influenza virus.
Given all these types of viral genomes, there is no option among A, B, C, and D that has not been observed as a chromosome of viruses.