Which payment method includes all cost factors for an entire project?

The payment method that includes all cost factors for an entire project is the lump sum method. Under a lump sum contract, the contractor agrees to complete the project for a fixed price, which is predetermined based on an estimate of total project costs, including materials, labor, overhead, and profit. This approach provides clarity to both parties as it defines the project's scope and total cost upfront.

This method is beneficial for clients who want a clear, all-inclusive price without the variability of additional costs that might arise during the project. It also requires the contractor to manage costs efficiently, as any overruns fall on their responsibility rather than the client's.

In contrast, other methods like cost-plus, percent completion, and unit price involve different pricing structures that can leave variable costs to be determined as the project progresses or is executed. For instance, a cost-plus arrangement allows contractors to bill for actual costs incurred plus a fee, which can lead to unexpected total project costs. The percent completion method tracks progress but bases payments on the percentage of work completed rather than providing a total project cost upfront. The unit price method involves pricing based on the completed quantity of work units, which also does not encapsulate all costs comprehensively.

Thus, the lump sum method is the correct choice