Based on the options provided, the most logical inference about the Gold Rush’s impact on San Francisco is:
The mass migration of forty-niners transformed San Francisco into an economic hub practically overnight.
This response suggests that the influx of people during the Gold Rush significantly changed the city's demographic and economic landscape, laying the groundwork for its growth and development. The other options imply limited or short-term effects, which does not align with the historical significance of the Gold Rush in San Francisco's transformation.