Final answer:
Polly can become eligible for the benefit of her long-term care rider if she is diagnosed as chronically ill due to either a medical or cognitive reason.
Step-by-step explanation:
For Polly to become eligible for the benefit of her long-term care rider, she must be diagnosed as chronically ill. According to the options provided, the diagnosis must be the result of either a medical or cognitive (mental health) reason. This means that option b) is correct. Polly can become eligible for the benefit if she is diagnosed as chronically ill due to either a medical or cognitive reason.