The Mystery of the Barking Dog

We re-rented the front of our house, and so we have new neighbors again.  They seem very nice.

They have a dog.  As part of discussion before move-in, I reminded them that we do not allow aggressive or excessively barky dogs.  I asked if their dog is aggressive or excessively barky.  They told me it isn't.  They said the dog does bark when people comes to the door, or if people invade the dog's territory, but otherwise it doesn't bark much. (That's acceptable.)

Over the past week or so they've been gradually moving in.  I can tell that they've brought the dog now, because it started barking around 1 pm today, and it has kept barking all day long--it's 8:15 pm as I type this and the wretched beast is still barking.

If you've ever met our dog, you'll know she is almost completely silent.  That's on purpose.  Jeff wanted a Chihuahua and I said "no way, Jose," because Chihuahuas are almost always extremely barky.  (Does anyone disagree with this?  Go visit the small dog room at the humane society and then visit the big dog room.)  The reason I screen for barky dogs before accepting a rental application for our house is because our last renters had a dog that was extremely barky and aggressive when he was outside, and moderately barky inside.  I hated it.

I don't mind hearing the neighbors' dog bark occasionally, but all day long??  Shouldn't it have a sore throat by now?


So, my dear friends, how did this happen??  Please vote.
a) The dog is adjusting to the new home and it will get much quieter very soon; it is not actually a barky dog.
b) The owners didn't realize their dog has a serious barking problem because it actually only barks when they are away, so they really do believe it is a quiet dog.
c) The owners lied or really exaggerated: the dog is barky and they knew it. (Asked about their dogs, how many owners would actually say, "Oh.  Actually our dog is very barky, so this may not work out.")
d) Someone has been knocking on the front door all day long and the dog is just barking about that.
e) It isn't their dog.  Someone else's dog is in the front of our house.
f) Some other reason. (Please explain in the comment space below.)

If this happens again tomorrow maybe I should text them to let them know there may be something wrong and they should probably check on their dog because it has been barking for x hours.  Or slip some poison under the laundry room door.  (Of course I could never actually do that, but my goodness, make the noise stop!)

And, for extra credit, will someone please explain to me why they keep making dogs like this?  If it were up to me, all barky or otherwise "bad" dogs would be neutered or spayed, and then sent to Australia to live out the rest of their miserable lives hunting wild rats and being eaten by fleas.