What are the adverse effects of manganese as a secondary contaminant?

The correct choice highlights the specific ways manganese can adversely affect the quality of water, particularly in its impact on aesthetics. Manganese can create discoloration issues, which are particularly noticeable in laundry, leading to staining, and it can alter the taste and appearance of beverages such as coffee and tea. These factors make the water unappealing, affecting not only its palatability but also its usability for various household tasks.

Manganese is not a health threat at the levels typically found in drinking water; however, its sensory characteristics can lead to consumer complaints. The discoloration and taste issues linked to manganese presence can significantly impact users' perception of water quality, even if it doesn't present health risks. Understanding these aspects is crucial for water treatment facilities to maintain water quality and public satisfaction.

In terms of the other possibilities, while they might touch on some effects of manganese, they do not encapsulate the comprehensive impact on beverages and laundry as indicated in the correct choice. Thus, option B provides the most relevant summary of manganese's adverse effects as a secondary contaminant in drinking water.