Which process would not be negatively impacted by microbial activity?

The correct answer is the process of water purification, as microbial activity plays a beneficial role in this context. In water purification, particularly in biological treatment processes like activated sludge or bioreactors, microorganisms break down organic pollutants and contaminants present in the water. This natural action helps to detoxify the water, making it cleaner and safer for reuse or discharge into the environment.

Microbial processes enhance the overall efficiency of water purification systems by degrading harmful substances and facilitating nutrient cycling. As such, microbial activity is integral to achieving high-quality effluent in these systems, underscoring the positive impact that microorganisms have in promoting and improving water purity rather than hindering it.

In contrast, bioremediation, food decomposition, and cropping systems could experience negative impacts from certain microbial activities, depending on the specific context or the types of microorganisms involved. Understanding the role of microbes in these processes highlights why water purification stands out as a process positively influenced by microbial activity.