why do many parts of the world need resources of water different from the ones used in United Kingdom?

Public water supply and sanitation in the United Kingdom is characterised by universal access and generally good service quality[citation needed]. A salient feature of the sector in the United Kingdom compared to other developed countries is the diversity of institutional arrangements between the constituting parts of the UK (England and Wales; Scotland; and Northern Ireland), which are each described in separate articles, while this article is devoted to some common issues across the United Kingdom.

the answer is d.) potassium