Which contract type places the MOST financial risk on the contractor?

Explanation

Under a fixed-price lump sum contract the contractor promises a finished result for one price, so every overrun - labor productivity, material escalation, rework - lands on the contractor. Cost-plus-a-fixed-fee reverses that: the owner reimburses actual costs and the fee is fixed, so the owner carries the overrun. Time and materials bills hours and materials as they are incurred, which again leaves the cost risk with whoever pays the invoices. A unit price contract fixes only the rate per unit installed; the quantity risk stays with the owner, and the contractor is exposed only on its own productivity per unit.