Which answer is the correct way to fix the following sentence?

slipping on the wet sidewalk, the keys fell from amaury’s pocket.

a.
when amaury slipped on the wet sidewalk, the keys fell from his pocket.
b.
slipping on the wet sidewalk the keys, fell from amaury’s pocket.
c.
when amaury slipped on the wet sidewalk the keys fell from his pocket.
d.
slipped on the wet sidewalk, the keys fell from amaury’s pocket.