Understanding the argument - The conclusion is that round shelves will not solve the purpose because such rotating shelves will have the same drawback. What drawback? The things would fall off the shelves edges into the rear corners.
Or we can look at it like this.
There is a problem - much-refrigerated food spoils because it ends up out of sight at the back of the shelf.
Solution - Let's have round shelves.
The conclusion says there is a problem with the solution or plan because such rotating shelves will have the same drawback. What drawback? The things would fall off the shelves edges into the rear corners.
One of the assumptions (which sounds ridiculous) is that we can't make the inside of the refrigerator cylindrical to fit the shape of rotating shelves. I said ridiculous because if someone proposed the round shelves, either they were dumb to fix the round shelves in the rectangular/square shape, or they provided an exquisite design with a cylindrical body and round shelves, but the author, instead of looking at the complete design, just looked at round shelves and gave a judgment that it's a ridiculous design assuming the interior body could not have been cylindrical. The reality could be that they acted dumb and, instead of looking at the complete design, gave judgment, making some ridiculous assumption. You'll say this happens regularly in our business dealings. That's why wisdom says to listen with two ears and speak with one mouth (listen more and speak less).
Sorry, I don't want to deviate from the topic. Let's quickly look at Option Elimination -
(A) Refrigerators would not be made so that their interior space is cylindrical. -ok. Solves the purpose.
(B) Refrigerators would not be made to have a window in front for easy viewing of their contents without opening the door. - It's talking about a different solution, which is not the scope of the argument. Out of scope.
(C) The problem of spoilage of refrigerated food is not amenable to any solution based on design changes. - "Any solution" is hyperbolic. We are just talking about just one solution, which is using rotating shelves. Distortion.
(D) Refrigerators are so well designed that there are bound to be drawbacks to any design change. - some general philosophy. Not relevant here. Out of scope.
(E) Rotating shelves would be designed to rotate only while the refrigerator door was open. - doesn't matter as the food can still fall off the corners, or it'll go opposite of what we are looking for in the sense if the food only falls when the door opens, there is a possibility that it's not out of sight as we see it falling (I know its to far fetched with a lot more assumptions). Linkage of shelves with the door open/closed - out of scope.