I totally agree with the option B being a really bad choice, but, the question says to pick the "lowest possible AWS cost" and this option allows the company to have no transfer cost since the S3 bucket will be configured with "Requester pays". I understood that this isn’t a good option for the real world, but, for the scenario described in the question, that answer would be valid. Can someone explain that a bit better for me? Am I missing some point?
If you want to make your customers pay, then go right ahead. As you said, it’s not feasible in the real world and that’s the world we live in.