Hello!
Your answer is A. A flagellate.
Flagellates are characterized as having flagella, which are whip-like projections (such as that in the diagram) which they use to propel themselves forward.
Ciliates are characterized as having cilia, which are hairlike structures that occur in larger numbers than flagella do on flagellates; they serve the same purpose as flagella - propulsion.
Amoebas have no definite shape and extend projections resembling fingers, unlike flagellates and ciliates.
I hope this helps you!