Octopus Den Size Selection - VIEWER REQUEST

Will our octopus choose the smallest den, the biggest den, or the one in between?
This experiment was requested by KZbin user Jonas Kirk. Here is what Jonas wrote:
“The little octopus dens featured in your videos are simply amazing. They made me think of an experiment…
What would happen if you placed different sized dens in an octopus's tank? Would he show preference to one of the sizes?"
"Place 3 of the octopus dens we see in your videos into a tank. The dens should preferably be of different sizes. See which of the dens he'll choose and then run the same experiment with the same dens placed in different positions. This should hopefully give us an answer as to which sized den he or she prefers.
I bet that in the wild there are a number of factors that influence the octopus in selecting its den. But what would happen if the only difference was the size of the octopus den?”
We presented a medium-sized octopus with three different den sizes, a big one, an average one, and a smaller one.
Octopuses in the wild have been observed to choose dens small enough so that they can maintain contact with the walls with all of their arms. Also, dens are relatively small, and they have a maximum volume two to three times that of the octopus. The size of the octopus is believed to be in proportion to the size of the den.
We were therefore expecting the octopus to go for either the small or the average sized den.
We rotated the position of the dens twice to make sure that proximity to a den was not an influencing factor.
It was fascinating to watch our octopus investigating its options and making a clear decision.
We hope that you enjoy watching this experiment and that you will keep contributing to our research with all your wonderful ideas!