Definition: In this task, you will be presented with a passage and have to answer a question based on your understanding of the events inferred from the passage. Try to find the best answer that is most likely to fill in "_". Note that the URLs in the text have been replaced with [Link].
Input: (CNN) -- On separate trips to Guatemala and Zambia in the late 1980s and in the early 2000s, we each saw the devastating effect of the water and sanitation crisis firsthand. We saw a world in which basic needs went drastically unmet -- where a lack of safe water and sanitation robbed men, women and children of health, hope and even life. In the time it takes us to fill a glass of water -- about 21 seconds -- a child in some part of the world has died because of water-related disease. Watch video: Gary White on the ubiquitous forceMatt Damon, Gary White: Millions die each year from lack of safe water and sanitationDamon, White: With WaterCredit program, we could help end the global water crisisThey say clean water access improve productivity, restore dignity and transform livesDamon, White: We hope more people will get involved with this big but solvable crisis 
 Question:Our research also shows that investment in _ reaches five to 10 times as many people as a traditional grant over a 10-year period.

WaterCredit