What type of contaminants can arise from natural or manmade sources of radiation?

The correct choice is radiological contaminants, which can originate from both natural and manmade sources of radiation.

Radiological contaminants include substances that emit radiation, such as uranium, radon, cesium, and strontium. These contaminants can be found in the environment due to radioactive decay processes, which occur naturally in minerals and certain soil types. Additionally, human activities, such as mining, nuclear power generation, and medical procedures that use radioactive materials, also contribute to the presence of radiological contaminants in the environment.

This type of contamination can pose significant health risks, making it crucial for water operators to monitor and manage levels of radiological contaminants in drinking water systems to ensure safety and compliance with regulatory standards.