Which country has natural arsenic water contamination?

1. A

   Sri Lanka

   Option (a) claims Sri Lanka has extensive natural arsenic water contamination. However, geological formations in Sri Lanka do not feature the specific deltaic arsenic-bearing sediments found in major river basins. Therefore, this option is incorrect.

2. B

   Bangladesh

   Option (b) claims Bangladesh has natural arsenic water contamination. Groundwater in Bangladesh is severely affected by natural arsenic poisoning due to the ingestion of Holocene alluvial sediments washed down from the Himalayas. This widespread geological phenomenon makes this option the correct key.

3. C

   Bhutan

   Option (C) claims Bhutan has natural arsenic water contamination. While mountainous regions face various water quality issues, widespread natural arsenic poisoning of groundwater is not a characteristic feature here. Thus, this option is incorrect.

4. D

   Pakistan

   Option (d) claims Pakistan has natural arsenic water contamination. Although localized contamination occurs in certain isolated tracts, it does not match the pervasive crisis seen in deltaic regions. Consequently, this option is incorrect.

Summary. Official key is (b) Bangladesh. Groundwater arsenic contamination is a major public health crisis caused by geological formations in the Bengal delta. Millions of tubewells draw water from upper sedimentary layers rich in arsenic minerals. Public health interventions and alternative water sources remain vital for affected populations. Understanding these hydrogeological conditions helps mitigate severe poisoning risks across South Asia.