Question

while using electron microscopy to examine the cell membrane of a bacterium, you have discovered the presence of a complex motor protein assembly. you do not find any evidence of a proper flagellum. you can conclude that the bacterium most likely has lost its ability to make
keratin.
flagellin.
tubulin.
actin.
myosin.

Explanation:

Flagellin is the main protein component of bacterial flagella. Since there is no proper flagellum and a motor - protein assembly is present, the most likely protein - making ability lost is for flagellin. Keratin is an animal protein, tubulin and actin are eukaryotic cytoskeleton proteins, and myosin is a motor protein in eukaryotes not related to bacterial flagella.

Answer:

B. flagellin