A Researcher Wanted to Determine If Consuming Diet Sodas Causes

A researcher wanted to determine if consuming diet sodas causes diabetes. He conducted a study in which subjects were asked to recall how many diet sodas they drank each day, on average; the subjects' blood sugar levels were then measured. The average blood sugar levels were determined in the test subjects. Each group included an equal number of male and female participants and the groups were standardized for average weight and age. Which of these statements most accurately describes what is seen in the graph?

A) There appears to be a positive correlation between the number of diet sodas consumed each day and the average blood sugar levels measured in mmol/L. However, no definite cause-effect relationship has been established.
B) There appears to be a negative correlation between the number of diet sodas consumed each day and the average blood sugar levels measure in mmol/L. However, no definite cause-effect relationship has been established.
C) Drinking four or more diet sodas each day causes diabetes; a definite cause-effect relationship has been established.
D) Drinking six or more diet sodas each day causes diabetes; a definite cause-effect relationship has been established.