What kind of people would sign up for the Public Option instead of health insurance?

Older - Younger? Unemployeed? The healthy or those with pre-existing conditions?
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People of ALL ages who want free health insurance, and people with low incomes, unskilled workers that don't get it with their jobs, the unemployed, and all the people with preexisting conditions that can get them covered cheaper - at least the first year - under government health care. IF it passes, it will be a huge, public lesson in "adverse selection".
Source