What organism is typically classified within the kingdom Plantae?

Kelp is correctly classified within the kingdom Plantae because it is a type of brown algae that is photosynthetic, utilizing sunlight to create its own food through the process of photosynthesis. Kelp grows in underwater forests in shallow ocean waters and shares many characteristics with terrestrial plants, including a complex multicellular structure and the presence of chlorophyll, which enables it to capture light energy.

Other choices do not belong to the Plantae kingdom. Mushrooms are part of the kingdom Fungi, which is distinct from Plantae and characterized by heterotrophic nutrition, meaning they obtain their food from other organic materials. Algae, while sometimes included in discussions related to plants, are a broad group that exists in different classifications, and not all are classified strictly within Plantae, especially since some are placed in the Protista kingdom. Bacteria belong to a completely different domain, characterized as prokaryotic organisms without a membrane-bound nucleus, which further differentiates them from the structures and functions observed in the Plantae kingdom.