Which of the following would be the most cost-effective approach to achieving improvements in hygiene and sanitation in a low-income, developing country? a. Promoting a community-based hand washing campaign

b. Building a piped water supply system

c. Building a sewer system

d. None of the above are cost-effective

B. Building a piped water supply system

Explanation: If we built the water system, nobody would be forced to use dirty water from rivers, lakes, etc. Everybody would be able to have access to clean water to not only wash with, but to drink, cook, and clean with as well. This would help the country with cleanliness as a whole.