The one-celled eukaryotic organisms above are often found in freshwater ponds. what is one
characteristic they all have in common?
a nucleus
b cilia
c flagellum
d pseudopodia

The correct option is A. Nucleus

Explanation:

The diagram in the question shows a paramecium, euglena and amoeba.

Paramecium can be describe as a fresh water animal which has a body covered with cilia. Flagellum and Pseudopodia lack in paramecium

Amoeba can be described as single celled organisms which have Pseudopodia for movement and shape changing.

Euglena is a single- celled organism capable of living is salt water as well as fresh water. It contains flagellum for movement but lacks cilia and Pseudopodia.

The structure common in all these organisms is the nucleus. Nucleus is present in every eukaryotic organism.

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