D. These products need to be purchased in huge lots and need to be stored in special conditions. The cost of procurement and strong is quite high.
Feedback The passage talks about the advantages in writing by using the new kind of pen and paper and arrives at a conclusion about the cost of clerical job. We have to show that the new products do not lead to decrease in cost of clerical job.
None of the choice (a), (c) and (e) has anything about the cost. Hence, none of them weakens the conclusion.
Choice (b) states that the new products can be manufactured and they also last longer. This information strengthens the conclusion.
According to choice (d) the procurement and storage costs are very high. This casts a doubt on the conclusion that the cost of clerical job can be decreased by using these new products. Hence, (d) weakens the conclusion.