Last year a record number of new manufacturing jobs were created. Will this year bring another record? Well, any new manufacturing job is created either within an existing company or by the start-up of a new company. Within existing firms, new jobs have been created this year at well below last year`s record pace. At the same time, there is considerable evidence that the number of new companies starting up will be no higher this year than it was last year and there is no reason to think that the new companies starting up this year will create more jobs per company than did last year`s start-ups. So clearly, the number of new jobs created this year will fall short of last year`s record.
In the argument given, the two portions in boldface play which of the following roles?
【选项】The first is a claim that the argument challenges; the second is an explicit assumption on which that challenge is based.