A digital payments startup is planning capacity for a data-quality project. Net service surplus equals total service capacity minus total expected arrivals. A valid pair must cost at most $237, have satisfaction at least 159, and have nonnegative service surplus. Data source options: Keystone data source (cost $62, expected arrivals 52, service capacity 97, satisfaction 60); Ridge data source (cost $97, expected arrivals 56, service capacity 92, satisfaction 82); Zenith data source (cost $121, expected arrivals 39, service capacity 67, satisfaction 97). Validation method options: Vector validation method (cost $140, expected arrivals 27, service capacity 116, satisfaction 91); Drift validation method (cost $141, expected arrivals 37, service capacity 89, satisfaction 64); Kestrel validation method (cost $109, expected arrivals 107, service capacity 110, satisfaction 77). Which valid pair gives the greatest service surplus?