What is a distinctive symptom associated with selenium and tellurium exposure?

The distinctive symptom associated with selenium and tellurium exposure is garlic breath. This odor is particularly noted for selenium exposure, which can lead to the production of volatile compounds such as dimethylselenide in the body. These compounds are responsible for the garlic-like smell in the breath of those exposed to high levels of selenium. This unique characteristic is a signaling feature and can help identify selenium exposure in a clinical setting. While tellurium exposure can also cause a garlic-like breath odor due to the formation of tellurium compounds, the more common association in occupational health diagnostics tends to highlight selenium.

Other symptoms mentioned, such as blackened teeth, yellow skin, and loss of appetite, are not specifically recognized as distinctive indicators of selenium or tellurium exposure and are more general symptoms that could arise from various other health conditions or exposures. Therefore, garlic breath serves as the hallmark symptom linking to selenium and tellurium, making it the correct answer.