Which one is peritrichous?
A. Pseudomonas
B. Bacillus typhosus
C. Spirillum
D. Vibrio

Hint: Bacteria belong to the kingdom Monera, and are the most abundant microorganisms found everywhere. They are non-motile and move by the beating of flagella. Based on the presence and absence of flagella, they are of many types.

Complete answer: Kingdom Monera comprises microscopic single-celled prokaryotic organisms of which bacteria are the sole members. Most bacteria bear a rigid cell wall. It consists of peptidoglycan, lipid proteins, amino acids, etc. Their genetic material is naked, circular DNA, and not enclosed by the nuclear envelope. It is called nucleoid or genophore. The ribosomes are the 70S. All membrane-bound organelles are absent and vacuoles do not occur. Instead, gas vacuoles may be present. Based on the presence or absence of flagella, the bacteria is of divided into the following categories:
a) Atrichous: when the flagellum is missing(absent)it is called atrichous.
b) Monotrichous: only one flagellum is found at one end.
c) Amphitrichous: when a single flagellum is present at both the ends.
d) Cephalotrichous: when a group of flagella(tuft) is present at one end only.
e) Lophotrichous: when a group of flagella is present at both ends.
f) Peritrichous: several flagella are present all over the body. For example E.coli, Bacillus typhosus, etc.
Hence, the correct answer is option B.

Note: Bacteria possess flagella for locomotion. They are the most primitive cells as compared to eukaryotes. They have a circular genetic material and a plasmid that is used as vectors in biotechnology.