Answer:
D. mycoplasma
Step-by-step explanation:
Active enzymes are not present in prions or viruses, as they are not considered living organisms and do not possess metabolic pathways for enzyme activity.
A. Viroids are infectious agents that consist of a small, circular, single-stranded RNA molecule without a protein coat. They do not have active enzymes, but can replicate within host cells using the host cell's enzymes.
B. Mycoplasma are bacteria that lack a cell wall and have limited metabolic pathways, but they do have active enzymes that are involved in various cellular processes, such as energy production, DNA replication, and protein synthesis.