Answer:
Eukaryotic
Step-by-step explanation:
The kingdoms of Protista and Animalia both fit under the general domain of Eukarya, which basically includes all eukaryotic animals. Eukaryotic animals are those whose cells have membrane-bound organelles and a nucleus.
Algae is a type of protist, so clearly it must be eukaryotic. Similarly, lions are part of the Animalia kingdom, so it also must be eukaryotic.
Thus, a common characteristic can be eukaryotic.
Hope this helps!