Which statement is not correct with respect to the formation of a tornado?
select one:
a. the wall cloud forms as the supercell draws in the high humidity air from the forward flank downdraft of the storm that rotates as it hits the ground. this forms a "wall" around the tornado as it forms.
b. the rear flank of the storm curls around the updraft and supplies the rotating air that forms the tornado. on radar this feature creates the hook echo
c. as the storm's updraft stretches upward, the rotation in the storm tightens causing the storm to spin faster.
d. the source of the tornado's rotation comes from the collision of cold canadian air and warm moist air from the gulf of mexico.