How do funnel clouds form ? A. cold air temperatures
B. tropical ocean waters
C. warm air that circles around
D. a gathering of dark clouds

i think A

Explanation:

Funnel clouds are caused by vertical stretching of vorticity. Vorticity can be thought of as "spin" in the atmosphere, which is usually produced by wind shear. As this vorticity is streched vertically the area of rotation shrinks and the spinning air speeds up.