Final answer:
The supportive nursing intervention is to provide accurate information and reassurance to the client experiencing anxiety about their lab results, being both informative and emotionally supportive.
Step-by-step explanation:
The question addresses the appropriate nursing intervention for a client experiencing anxiety about laboratory test results. The most supportive intervention a nurse can provide in this situation would be option b) Provide accurate information and reassurance. This approach acknowledges the client's feelings and offers comfort while delivering factual information to help alleviate concerns. It is important for healthcare professionals to listen to patients' concerns, provide emotional support, and deliver clear communication regarding healthcare matters.