Final answer:
If the owner or architect objects to a subcontractor that the contractor proposes and a more expensive sub needs to be hired, the contractor typically pays for the difference. The correct option is a.
Step-by-step explanation:
In construction projects, if the owner or architect objects to a subcontractor proposed by the contractor and the contractor has to hire a more expensive subcontractor, the cost difference is typically paid by the contractor.
When a subcontractor is hired, it is usually the responsibility of the contractor to select and manage them. Therefore, any additional costs resulting from a change in subcontractor would be the contractor's responsibility.
It is important for contractors to carefully consider and propose qualified subcontractors to avoid objections and potential cost increases.