Final answer:
An individual with serious and persistent mental illness who prefers to focus on the activity rather than on other group members should participate in a task-oriented group that enables her to have her own space and materials, with minimal verbal exchange.
Step-by-step explanation:
The individual with serious and persistent mental illness, who prefers to focus on the activity rather than on the other group members, would benefit from participating in a task-oriented group that provides her with her own space and materials, and allows for minimal verbal exchange. This type of group would be suitable because it allows the individual to engage in the activity at her own pace and comfort level, while still being part of a supportive and structured environment.