Answer:
B) Cell walls are made primarily of peptidoglycan.
Step-by-step explanation:
The presence of peptidoglycan in the cell walls of the organism is enough to classify the organism as belonging ot bacteria.
A is incorrect because being unicellular is not exclusive to bacteria only. Members of Archaea and some members of Eukarya are also unicellular.
C is not correct because because the component of the plasma membrane is similar in the three classes of organisms.
D is not correct because only members of Archaea have the ability to survive in extreme environments such as very high temperature.
E is incorrect because both bacteria and archaea lack nucleus.
The correct option is B.