D.. I think. Although it's long, it best expresses the meaning of the two sentences it combined.
Repeating a sequence of words at the beginning of a phrase is called 'Anaphora' in rhetoric. It is used in speeches to give emphasis to the point being discussed. Thus, the speaker wanted to emphasize his point and encourage his listeners to do something as well.
Using the formula:

Which is, 3.14 x 2^2 (radius is half of diameter)
Which equals 12.56.