Scientist Chick found that there was a clear link between body mass index (BMI, a method of measuring weight and weight) and memory decline. In experiments, participants with higher BMI performed worse. Kick's findings suggest that obesity can cause brain atrophy and memory loss. Which of the following, if true, would most challenge the above conclusions? ['Surgery transplanted obese abdominal fat into lean mice, and found that these fats caused brain inflammation in lean mice, altered synaptic function, and caused cognitive impairment in the transplanted mice.', 'A brain scan study involving 500 participants confirmed that obesity is closely related to brain degradation caused by aging, and this effect is particularly pronounced in middle-aged people.', 'A medical school reports that the hippocampus is located deep in the brain and is responsible for learning and memory functions. Middle-aged people with higher abdominal fat content have a smaller hippocampal capacity than lean people.', 'Some scientists have found that people who are distracted at lunch have a vague memory of lunch, which causes them to feel hungry and eat more at dinner. It is concluded that memory defects can cause weight gain.']