Stroll means to walk in a leisurely way. Move means go in a specified direction or manner; change position. Gallop means the fastest pace of a horse or other quadruped, with all the feet off the ground together in each stride. While the first two options do not convey the intensity with which the thief would react on seeing the police, third option gallop is used only for horses or other quadruped. Hence, option (d) 'ran' seems most appropriate.