What are the four main delivery contract methods in construction?

The four main delivery contract methods in construction are correctly identified as Design Bid Build, Multiple Prime, CM at Risk, and Design Build.

Design Bid Build is the traditional method where the design is completed before contractors are invited to bid on the construction. This method promotes clear delineation of responsibilities and phases but may lead to increased costs and time if changes are needed.

Multiple Prime allows various contractors to be hired separately by the owner for different scopes of work, promoting specialized expertise but requiring more management from the owner to coordinate multiple contracts.

CM at Risk involves a construction manager who commits to completing the project within a guaranteed maximum price, thereby providing cost control and schedule adherence while allowing for collaboration during the design phase.

Design Build consolidates both design and construction services under one contract, streamlining communication and potentially reducing project time but necessitating careful selection of a design-build team.

The other options list methods or terms that are not part of the main delivery methods in a standardized sense. For instance, Fixed Price and Time and Materials are types of pricing contracts rather than delivery methods, while Change Orders pertain to modifications in existing contracts, and Unit Price is more of a pricing strategy.