Which factor is difficult to assess in a cost-benefit analysis?

In a cost-benefit analysis it is very difficult to assess the benefits of the product used by everyone. The benefit of the cost is nothing but adding up the costs comparing them with the benefits to get a real value. All other options are included in calculating the cost-benefit except the option “A”.

emerging idea only occurs as a raw idea that could appear out of nowhere. meanwhile, to reach scientific consensus , that idea must be structured and tested over and over again through various experiments. the scientific consensus transforms the raw idea into idea that is more reliable through the process of scientific elimination.