Final answer:
The question addresses the characteristic of Euglena, a flagellated protozoaire, which moves using flagella, making 'B. flagella' the correct choice.
Step-by-step explanation:
The question pertains to the characteristics of a protist known as Euglena, which is a flagellated protozoaire. When analyzing the details provided, including the reference to Euglena having two flagella for movement and the term 'protozoaire flagellé', we can deduce that the correct answer is B. flagella. Euglena is known for its unique features, including a red 'eyespot' and a pellicle, which gives it exceptional flexibility in its movements. Flagella are critical for Euglena's locomotion, allowing it to propel itself through aquatic environments.