Read the passage carefully and select the best answer to each question out of the given four alternatives.
Passage:

Malnutrition affects millions of people worldwide and is responsible for one-fifth of deaths in children under the age of five. Children can also experience impaired cognitive development and stunted growth.
According to Finlay and UBC PhD student Eric Brown, malnutrition can be difficult to treat because it affects the good bacteria that live in the gut. People suffering from malnutrition often show signs of a disease known as environmental enteropathy, which is an inflammatory disorder of the small intestine and is likely caused by ingesting pathogenic fecal bacteria early in life from a contaminated environment. This shifts the balance of the original healthy bacteria in the gut and leads to poor absorption of nutrients.
The study, published in Nature Communications, explains how the research team developed a mouse model to reproduce the symptoms of environmental enteropathy and malnourishment.
“We were able to see how a malnourished diet has a strong, measurable impact on the microbes in the small intestine,” said Brown. “This new model gives us the opportunity to examine the impact of malnutrition on gut microbiology and assess the role of infections.”
Pathogenic bacterial infections like salmonella and E. coli are huge problems in developing countries because they are much more harmful to people suffering from malnutrition, leading to chronic diarrhea and inflammation.
“Treatments and vaccines created in developed nations and tested on healthy people often don't work in malnourished populations,” said Finlay, distinguished professor at UBC's Peter Wall Institute for Advanced Studies. “People suffering from malnutrition respond differently.”
With an animal model, Finlay said researchers will be better able to test treatments and understand how malnutrition impacts a child's development.