These boots were made for (walking off with)

I can now add "Randomly getting rid of grad students' belongings" to my job description. Let me explain.
We have a lab that is mainly used for storage, but it is about 2/3 full of junk belonging to people who were here years ago. Ever so often I get a bee in my bonnet and go in and clear it out a bit. I haven't really gotten rid of too much, because I actually am worried about getting rid of something important.
Mixed in with the random personal belongings of the former main inhabitant of the lab were a pair of cheap hiking boots. Everyone, including my boss, would make jokes about the boots, if they happened to wander in when I was in there. The boots were always there, and it never seemed like anyone was wearing them
My boss had salvaged some storage racks, which got moved in there today. I was in procrastination mode, so I wandered in there to see what was up. My boss was also in procrastination mode, so he wandered in too. We once again joked about the boots, which had gotten displaced by the storage racks. I told him I was going to get rid of the boots.
The chemistry department has a "free table" where people can get rid of or acquire surplus stuff. In theory this is just chemistry stuff, but people put all manner of stuff on there and most of it gets taken. I put the boots, and some very old textbooks, on the free table. I didn't really think that the boots would get taken, but put them there just to assuage my guilt about throwing them away.
Later that night, a grad student, "M", came by my office and asked if I knew what happened to his boots. Oh shit! He wears them to/from the lab every day during the winter. We went down to the free table but they were gone. I told him I'd reimburse him for a new pair and I put up a sign in case the boots might get returned by their new owner. The next morning, someone had put the boots back on the table and M reclaimed them. All's well that ends well.
So anyway, I was chagrined and mortified, but it's also funny as hell and the whole group laughed their asses off about it, even the guy who lost the boots.
So, what is the funniest part of the whole story?

A: that someone took the old boots within a few hours?
B: that no one knew that M owned the boots because he cleaned them up so well each time that I never saw any new dirt or water on them, and they were always in the same place? (M is German and very meticulous)
C: that the boots were always there because M is always in lab?