You don't have to answer this I just have to copy and paste my answer for a previous question because someone keeps being a donkey and reports me for no reason. B.) Performing a tensile test.

I say this is the answer because they are attaching objects to the ceiling and it wouldn't make sense for them to be testing the weight of the objects whereas there is no scale to monitor it. Attaching weights wouldn't to the ceiling measure the height of the ceiling. That leaves the only logical answer to be B.

Hope this helps and have a nice day.

-R3TR0 Z3R0