A bacterium with a tuft of flagella at both poles is called:

Explanation

OPTION A: A lophotrichous bacterium has a group of two or more flagella inserted at one pole of the cell. OPTION B: In peritrichous bacterium, flagella are dispersed on the entire surface of the cell. OPTION C: A monotrichous bacterium possess a single flagellum. OPTION D: An amphitrichous bacterium is characterized by groups of flagella inserted at both ends of the cell. Hence, D is the correct option.