A Group of Participants Were Split into Two Groups

A group of participants were split into two groups. The first group was asked: What is your best guess about the average height of Redwood trees? Is it more or less than 800 feet? The second group was asked: What is your best guess about the average height of Redwood trees? Is it more or less than 200 feet? The average response for the first group was 600 feet while that for the second group was 400 feet. On the basis of this, you would argue that the anchoring index in this case is:

A) 0.5 or 50%.
B) 1 or 100%.
C) 0.67 or 67%.
D) 1/3 or 33.33%.