Final answer:
Amoebas are characterized by their use of pseudopodia, which are lobe-like extensions that allow them to move and feed. These are different from cilia and flagella used by other organisms for locomotion. The correct answer is (d) pseudopodia.
Step-by-step explanation:
The cellular structure characteristic of amoebas is pseudopodia. Amoebas use these lobe-like extensions to move and anchor themselves to surfaces. Unlike other structures such as cilia, which are hair-like appendages used by organisms like Paramecium for locomotion, or flagella, which are whip-like tails used by organisms like Euglena for propulsion, pseudopodia are unique to amoebas and some other organisms that use them for movement and feeding.
When an amoeba moves, it extends a pseudopodium towards the direction in which it wants to move and then the rest of the cell's contents flow into this extension. This method of movement is known as amoeboid motion. Therefore, the correct answer to which of the following cellular structures is characteristic of amoebas is (d) pseudopodia.