The following options are attached to the question above:
A. A unicellular prokaryote
B. The shell surrounding a pilus
C. A type of virus
D. A particle that attacks viruses
ANSWERS
The correct option is A.
Bacteria are unicellular organisms, which have no true nucleus and they possess simple internal structures. They are microscopic organisms and they can be found in diverse places such as in the soil, ocean, in the human gut, in the air, etc. Bacteria are usually very small in size and large number of them usually exist together as a community. Bacteria are responsible for a large number of diseases in plants, animals and humans.