What Do Most Economists Think Is the Most Accurate Statement

What do most economists think is the most accurate statement about velocity?

A) It is fairly constant in the short run, but varies considerably in the long run, complicating predictions about nominal GDP.
B) M1 velocity is more stable in the short run than M2 velocity, and it has been a superior tool in predicting changes in nominal GDP.
C) It is not constant in the short run, and predictions about nominal GDP have not fared well.
D) M2 velocity has been less stable than M1 velocity, but both are reliable enough to make accurate predictions about changes in nominal GDP.