Final answer:
Fimbriae are critical for bacterial growth on the surface of teeth because they allow bacteria to adhere to surfaces and form biofilms.
Step-by-step explanation:
When considering the growth of bacteria on the surface of teeth, the most important cellular structures would be those that enable bacteria to attach to surfaces and potentially to other cells. Based on what we know about prokaryotic cell structures, the correct answer here is B. Fimbriae. Fimbriae are short bristle-like proteins that project from the bacterial cell surface, sometimes by the hundreds, to facilitate adherence to surfaces and other cells. This attachment is key for colonization and the formation of biofilms, such as dental plaque on teeth.