A Work Associate Leaves His Bike Each Day in Your

A work associate leaves his bike each day in your garage while both of you commute to work in your car. (This associate pays $5 per day for riding in your car.) One day the bike is stolen out of your locked garage. Are you responsible for the loss of this bike?

A) No, since it was gratuitous bailment with a low standard of care.
B) Yes, since it was stolen from your property.
C) No, because you met the standard of care required.
D) Yes, because your home owner's insurance will pay for it.
E) No, because your work associate automatically assumed this risk.