An 'incidental beneficiary' of a contract differs from an intended beneficiary in that an incidental beneficiary:

解析

Civil Code §1559 gives a contract 'made expressly for the benefit of a third person' the right to be enforced by that person — 'expressly' is the word doing the work. A third party who merely gains because the contract exists is incidental and has no claim: the neighbour whose property value rises when you remodel, the supplier who expects more orders if the job goes ahead. (c) describes the INTENDED beneficiary, the contrast this question turns on; a subcontractor named as a payee, or an owner named in a subcontract, can sue on it. (a) is wrong twice over — the owner is usually a party to the prime contract and an intended beneficiary of the subcontracts. (d) invents a consent right; no beneficiary, intended or incidental, controls the parties' changes.