Final answer:
Option (c), Pontiac's former allies turned against him due to British influence, as Britain's political strategies and the diminishing hope for French support weakened tribal unity and confederacy.
Step-by-step explanation:
The question asks why Pontiac's former allies turned against him during Pontiac's War. The factors leading to the dissolution of alliances within Pontiac's confederacy were complex. However, the correct option from the ones provided is c) British influence. British strategies included manipulating tribal rivalries and the spreading of diplomatic gifts, creating dissent among different Native American groups.
The British influence, though not overtly mentioned in provided options, is a clear historical driver of breaking tribal unity. The British exerted pressure on the allies through promises, threats, and political maneuvers. Moreover, as Pontiac's hope for French support diminished, the sustainability of widespread tribal resistance weakened, further leading to the erosion of his confederacy.