Which of the following is a transboundary water challenge?

• A. Domestic water pricing within a single city.
• B. Pollution in shared basins that cross borders.
• C. Rainwater harvesting in a single country.
• D. Groundwater pumping within one province.

Answer: (B)

Transboundary water challenges come from water resources that cross political borders, creating shared stakes and the need for cooperation among different jurisdictions. Pollution in basins that cross borders exemplifies this because contaminants in a river or lake affect multiple countries or regions relying on the same water body, requiring cross-border monitoring, treaties, and joint pollution control to protect water quality for all users. The other situations describe issues contained within a single jurisdiction—pricing water domestically, collecting rainwater within one country, or pumping groundwater within one province—so they don’t involve cross-border coordination or shared resources.