Final answer:
The subject of this question is History because it pertains to the founding of an organization based on the life and work of St. Vincent de Paul, serving the poor.
Step-by-step explanation:
The subject of this question is History because it pertains to the founding of an organization based on the life and work of St. Vincent de Paul. This topic falls under the domain of history as it involves understanding the historical context and the actions taken to serve the poor.