Final answer:
The patricians and equites had more power in Roman society, with the senators being predominantly from the patrician class.
Step-by-step explanation:
In Roman society, the groups that had more power were the patricians and the equites (or knights). The patricians were the aristocratic elite who held public office and sat in the Senate, while the equites were the wealthy class that benefited from trade and commerce. The term that best completes the diagram would be B. Senators, as senators were predominantly from the patrician class and held considerable power in Roman society.