Which of the following is true about microorganisms?

Microorganisms play a diverse role in various ecosystems, and their impact can range from beneficial to harmful. The statement that they can be helpful is accurate because many microorganisms, such as bacteria, fungi, and certain protists, contribute positively to human health, agriculture, and the environment. For instance, beneficial bacteria in the human gut microbiome aid in digestion and nutrient absorption, while certain fungi are crucial in decomposing organic matter and recycling nutrients in ecosystems. These examples illustrate the essential symbiotic relationships that many microorganisms have with other living organisms, highlighting their positive roles.

The other options do not adequately reflect the complexity of microorganisms. While some microorganisms are indeed harmful and can cause diseases, others are integral to various processes that sustain life. Additionally, microorganisms can mutate, which allows them to adapt to changing environments and develop resistance to treatments. They also exist in numerous environments beyond humans, including soil, water, and air, demonstrating their vast diversity and ecological significance. Thus, recognizing that microorganisms can be helpful underscores the importance of understanding the multifaceted roles they play.