Answer:
Because Ulva is an algae. Algae belongs to kingdom Protista.
Explanation:
Ulva is a Macroalgae because it's not microscopic.
Macroalgae is not considered as a plant due to their structure. Macroalgae do not have specialized organs and tissues, and they are not vascularized. They also do not have the capacity to form a structure with flowers, leaves, roots or a stem.
