Final answer:
Archeocytes/choanocytes use RNA interference mechanisms to prevent mobile elements in the genome, which involves small interfering RNAs targeting and neutralizing complementary mRNA molecules to impede protein synthesis.
Step-by-step explanation:
The question pertains to the mechanisms by which archeocytes/choanocytes might prevent mobile elements in the genome from causing harm or disruption. Among the options provided, the correct answer is RNA interference mechanisms (A). This natural regulatory mechanism involves RNA interference (RNAi), where small interfering RNAs (siRNAs) base pair with complementary mRNA molecules to prevent protein synthesis. RNAi helps to protect cells from the potential damages of viral invasion and transposon activity by targeting these foreign or mobile elements and preventing their replication within the host genome. While the other options like DNA repair enzymes, epigenetic modifications, and telomere extension mechanisms are important for maintaining genomic integrity and stability, they do not directly prevent the activity of mobile elements in the same way as RNA interference.