Answer:
amoeba
Step-by-step explanation:
Amoebas are organisms that are just basically jelly and a nucleus. There's an attached picture.
That "jelly" is called protoplasm; it's the fluid that makes up the amoeba's body.
Why not A: vacuoles are just protoplasm, no nucleus. they're not organisms.
Why not C: bacteria have no nucleus; they have a nucleoid region.
Why not D: a pseudopodium is an extension of an amoeba, kind of like a retractable arm.