Final answer:
Washington members of Kaiser Permanente should use the website www.kpwa.org for region-specific health information and services.
Step-by-step explanation:
The website that Washington members should use for Kaiser Permanente is option b) www.kpwa.org. This is the specific portal for Washington State residents offering integrated health services and information. Other regional websites from Kaiser Permanente might not provide the same tailored information and services needed by members in Washington.