Fact 1: Prokaryotes are single-celled organisms that lack a nucleus.

Fact 2: Bacteria and archaebacteria are prokaryotes.

Given the two facts above, answer the question "Bacteria and archaebacteria examples of what?" with the following options: 
- grass
 - multi-celled organisms
 - seeds
 - Something that causes allergies
 - major threat to health
 - single-celled organisms
 - microorganisms
 - Food poisoning


 

      single-celled organisms   