Understanding the argument -
There is no reason why the work of scientists has to be officially confirmed before being published. - Conclusion. It says, "There is no reason to do this."
There is a system in place for the confirmation or disconfirmation of scientific finding, namely, the replication of results by other scientists. - Supporting premise.
Poor scientific work on the part of any one scientist, which can include anything from careless reporting practices to fraud, is not harmful. - Fact
It will be exposed and rendered harmless when other scientists conduct the experiments and obtain disconfirmatory results. - Opinion and supporting premise.
Option Elimination - Weaken
(A) Scientific experiments can go unchallenged for many years before they are replicated. - If this is the case, then this is a big reason. Ok.
(B) Most scientists work in universities, where their work is submitted to peer review before publication. - Strengthener.
(C) Most scientists are under pressure to make their work accessible to the scrutiny of replication. - Strengthener. If they are under pressure to ensure that it can be replicated, they'll do everything beforehand to ensure it's correct. So, there is no reason for the official confirmation.
(D) In scientific experiments, careless reporting is more common than fraud. - This comparison is out of scope.
(E) Most scientists work as part of a team rather than alone. - Strengthener.