Henry Was Burning Leaves in His Backyard

Henry was burning leaves in his backyard. One of the burning leaves was lifted by the wind into Bob's yard next door. It landed on the lawnmower which exploded, setting fire to the wooden lawn furniture. Henry's best argument against liability to Bob would be:

A) the leaf was not a substantial factor in causing the damage.
B) the gasoline in the lawnmower is a superseding cause of the damage.
C) it was not foreseeable that the lawnmower would explode.
D) the damage was not caused by the leaf but by the gasoline.