What are protists?

Protists are primarily characterized as a diverse group of eukaryotic microorganisms that are typically unicellular but can also be multicellular without having specialized tissues. Option B, which mentions microorganisms like malaria, accurately identifies protists because malaria is caused by a type of protist called Plasmodium.

These organisms often play various roles in ecosystems, including being part of the food web and contributing to nutrient cycling. Many protists are indeed pathogenic, affecting not only humans but also animals and plants, albeit the specific mention of malaria makes it clear that this option emphasizes the pathogenic aspect of some protists.

While the other options do not correctly represent protists — as they either limit the definition too narrowly to multicellular forms, focus solely on plant pathogens, or suggest an inability to reproduce — option B encompasses a key aspect of the protist category, highlighting their role as microorganisms involved in significant diseases, including malaria, thus providing a clearer understanding of these organisms.