Why did the political balance between Caesar and Pompey grow unstable after Crassus died in 53 BCE?
Crassus had held sole legal authority binding the Senate to honor the alliance
Pompey's own death that year left Caesar without any rival
The three-way alliance had rested on shared influence among Caesar, Pompey, and Crassus, and with Crassus gone only two rivals for supreme power remained✓الإجابة الصحيحة
The Senate had formally outlawed cooperation between two sitting consuls
الشرح
Once Crassus died, the coalition's balance among three powerful figures collapsed into a direct contest between Caesar and the remaining triumvir for pre-eminence. Crassus had no special legal power over the Senate, the other ally remained alive in 53 BCE, and no law barred cooperation between serving magistrates.