In addition to being parasitic, what other relationships can protozoa have?

Protozoa can have a variety of ecological relationships beyond being purely parasitic. In addition to their role as parasites, which can have detrimental effects on their hosts, protozoa can also engage in commensal and mutualistic relationships.

In a commensal relationship, one organism benefits while the other is neither helped nor harmed. Some protozoa inhabit the intestines of animals and can help in the digestion of food without affecting the host adversely.

In mutualistic relationships, both organisms benefit from their association. Certain protozoa live in symbiosis with other species, contributing to essential processes such as nutrient cycling or helping to break down complex materials, which in turn provides benefits to the host.

Understanding these varied interactions highlights the ecological diversity of protozoa and emphasizes that their role in ecosystems is more complex than solely causing disease. Therefore, "All of the above" correctly captures the spectrum of relationships protozoa can have, including parasitic, commensal, and mutualistic interactions.