Recent research has demonstrated a correlation between the presence of certain types of Gram-positive bacteria in the human gut with obesity and type 2 diabetes. These findings best support which of the following statements?

a. Normal microbiota may significantly impact human health and disease
b. The presence of Gram-positive bacteria in the human gut causes obesity and type 2 diabetes
c. Gram-positive bacteria compose the majority of normal microbiota in the human gut of people with obesity and type 2 diabetes.
d. Obesity and type 2 diabetes are caused by normal microbiota in the human gut