Which of the following statements is evidence in the form of a research study?

“People should not eat fast food because it is expensive and tastes bad.”
“My sister works at the local burger joint, and she tells me that her customers eat too much fast food.”
“Fast food is unhealthy and it leads to illnesses such as diabetes and heart disease.”
“The FDA conducted a test of the American diet, and it concluded that Americans who eat excessive amounts of fast food suffer from health issues such as diabetes, obesity, and heart disease.”