Answer:
b. partially melted snow or ice.
A
Step-by-step explanation:
A slush is typically a melted snow that's mixed with dirt to form a brownish color.
From the sentence above, it is said that his luggage arrived through the slush and it was a very remarkable luggage indeed. So it is evident that the luggage was covered in a generous amount of partially melted snow for the luggage to have been a remarkable sight.