When You Blow on a Pinwheel, It Starts to Spin

Multiple Choice

When you blow on a pinwheel, it starts to spin. Even when you aim the air directly toward the wheel's pivot you produce a torque on the wing-like blades and they undergo angular acceleration. This torque is produced by

A) lift forces on the pinwheel's blades.
B) a deflection of the air stream directly away from the pivot.
C) the buoyant force due to the high pressure air hitting the blades of the pinwheel.
D) drag forces on the pinwheel's blades.