Based on the provided options and considering common historical interpretations of the Gupta Empire, the most consistent conclusion that can be drawn is:
The Gupta Empire expanded through military force and political deals.
This conclusion aligns with historical accounts that describe the Gupta Empire's methods of expansion, which often included military conquests as well as strategic alliances and marriages with neighboring states. The other options suggest isolation or solely peaceful relations, which do not accurately reflect the historical context of the Gupta Empire's growth and interactions with other kingdoms.